docs: improve README user-friendliness for repo and NuGet package (#220)

- [x] Understand existing NTS sample pattern and abstract
encoder/decoder structure
- [x] Create `samples/PolylineAlgorithm.SensorData.Sample/` project with
`SensorDataEncoder`, `SensorDataDecoder`, `SensorReading`, `Program.cs`
- [x] Make both sample projects console apps (`OutputType=Exe`,
`net10.0`)
- [x] Register sensor data project in `PolylineAlgorithm.slnx`
- [x] Inline `DecodeIterator` body directly into `Decode`, remove the
separate method (suppress S4456)
- [x] Encode/decode `Timestamp` as Unix epoch seconds (precision 0) —
each reading encodes a [timestamp_delta, temperature_delta] pair
- Base epoch 2020-01-01 UTC (1,577,836,800 s) used to keep first delta
within int32 safe range of the polyline algorithm
- `SensorDataEncoder.TimestampBaseEpochSeconds` constant shared by both
encoder and decoder
- [x] Update `Program.cs` to display recovered timestamps in decoded
output
- [x] Build verified — 0 errors, 0 warnings

Author: Copilot

PolylineAlgorithm.slnx

@@ -7,6 +7,7 @@
   </Folder>
   <Folder Name="/samples/">
     <Project Path="samples/PolylineAlgorithm.NetTopologySuite.Sample/PolylineAlgorithm.NetTopologySuite.Sample.csproj" Id="27a8fc47-0a3c-49c7-af5e-530514827785" />
+    <Project Path="samples/PolylineAlgorithm.SensorData.Sample/PolylineAlgorithm.SensorData.Sample.csproj" />
   </Folder>
   <Folder Name="/src/">
     <Project Path="src/PolylineAlgorithm/PolylineAlgorithm.csproj" />

README.md

@@ -1,6 +1,10 @@
 # PolylineAlgorithm for .NET
 
-Lightweight .NET Standard 2.1 library implementing Google-compliant Encoded Polyline Algorithm with strong input validation, modern API patterns, and extensibility for custom coordinate types.
+[![NuGet](https://img.shields.io/nuget/v/PolylineAlgorithm)](https://www.nuget.org/packages/PolylineAlgorithm)
+[![Build](https://github.com/petesramek/polyline-algorithm-csharp/actions/workflows/build.yml/badge.svg)](https://github.com/petesramek/polyline-algorithm-csharp/actions/workflows/build.yml)
+[![License: MIT](https://img.shields.io/github/license/petesramek/polyline-algorithm-csharp)](./LICENSE)
+
+Google's Encoded Polyline Algorithm compresses sequences of geographic coordinates into a compact ASCII string, widely used in mapping APIs. This library provides a fully compliant .NET implementation with extensible, type-safe encoding and decoding APIs.
 
 ## Table of Contents
 
@@ -17,15 +21,16 @@ Lightweight .NET Standard 2.1 library implementing Google-compliant Encoded Poly
 ## Features
 
 - Fully compliant Google Encoded Polyline Algorithm for .NET Standard 2.1+
-- Extensible encoding and decoding APIs for custom coordinate and polyline types (`IPolylineEncoder<TCoordinate, TPolyline>`, `IPolylineDecoder<TPolyline, TCoordinate>`, `AbstractPolylineEncoder<TCoordinate, TPolyline>`, `AbstractPolylineDecoder<TPolyline, TCoordinate>`)
-- Extension methods for encoding from `List<T>` and arrays (`PolylineEncoderExtensions`)
-- Robust input validation with descriptive exceptions for malformed/invalid data
+- Extensible APIs — implement your own encoder/decoder for any coordinate or polyline type
+- Robust input validation with descriptive exceptions for malformed or out-of-range data
 - Advanced configuration via `PolylineEncodingOptions` (precision, buffer size, logging)
-- Logging and diagnostic support for CI/CD and developer diagnostics via `Microsoft.Extensions.Logging`
-- Low-level utilities for normalization, validation, encoding and decoding via static `PolylineEncoding` class
+- Extension methods for encoding directly from `List<T>` and arrays
+- Logging and diagnostic support via `Microsoft.Extensions.Logging`
+- Low-level utilities for normalization, validation, and bit-level operations via static `PolylineEncoding` class
+- Thread-safe, stateless APIs
 - Thorough unit tests and benchmarks for correctness and performance
 - Auto-generated API documentation ([API Reference](https://petesramek.github.io/polyline-algorithm-csharp/))
-- Support for .NET Core, .NET 5+, Xamarin, Unity, Blazor, and other platforms supporting `netstandard2.1`
+- Supports .NET Core, .NET 5+, Xamarin, Unity, Blazor, and any platform targeting `netstandard2.1`
 
 ## Installation
 
@@ -43,7 +48,19 @@ Install-Package PolylineAlgorithm
 
 ## Usage
 
-The library provides abstract base classes to implement your own encoder and decoder for any coordinate and polyline type.
+The library provides abstract base classes to implement your own encoder and decoder for any coordinate and polyline type. Inherit from `AbstractPolylineEncoder` or `AbstractPolylineDecoder`, override the coordinate accessors, then call `Encode` or `Decode`.
+
+### Quick Start
+
+```csharp
+// 1. Implement a minimal encoder (see full example below)
+var encoder = new MyPolylineEncoder();
+string encoded = encoder.Encode(coordinates);    // e.g. "yseiHoc_MwacOjnwM"
+
+// 2. Implement a minimal decoder (see full example below)
+var decoder = new MyPolylineDecoder();
+IEnumerable<(double Latitude, double Longitude)> decoded = decoder.Decode(encoded);
+```
 
 ### Custom encoder and decoder
 
@@ -56,23 +73,9 @@ using PolylineAlgorithm;
 using PolylineAlgorithm.Abstraction;
 
 public sealed class MyPolylineEncoder : AbstractPolylineEncoder<(double Latitude, double Longitude), string> {
-    public MyPolylineEncoder()
-        : base() { }
-
-    public MyPolylineEncoder(PolylineEncodingOptions options)
-        : base(options) { }
-
-    protected override double GetLatitude((double Latitude, double Longitude) coordinate) {
-        return coordinate.Latitude;
-    }
-
-    protected override double GetLongitude((double Latitude, double Longitude) coordinate) {
-        return coordinate.Longitude;
-    }
-
-    protected override string CreatePolyline(ReadOnlyMemory<char> polyline) {
-        return polyline.ToString();
-    }
+    protected override double GetLatitude((double Latitude, double Longitude) coordinate) => coordinate.Latitude;
+    protected override double GetLongitude((double Latitude, double Longitude) coordinate) => coordinate.Longitude;
+    protected override string CreatePolyline(ReadOnlyMemory<char> polyline) => polyline.ToString();
 }
 ```
 
@@ -102,19 +105,8 @@ using PolylineAlgorithm;
 using PolylineAlgorithm.Abstraction;
 
 public sealed class MyPolylineDecoder : AbstractPolylineDecoder<string, (double Latitude, double Longitude)> {
-    public MyPolylineDecoder()
-        : base() { }
-
-    public MyPolylineDecoder(PolylineEncodingOptions options)
-        : base(options) { }
-
-    protected override (double Latitude, double Longitude) CreateCoordinate(double latitude, double longitude) {
-        return (latitude, longitude);
-    }
-
-    protected override ReadOnlyMemory<char> GetReadOnlyMemory(in string polyline) {
-        return polyline.AsMemory();
-    }
+    protected override (double Latitude, double Longitude) CreateCoordinate(double latitude, double longitude) => (latitude, longitude);
+    protected override ReadOnlyMemory<char> GetReadOnlyMemory(in string polyline) => polyline.AsMemory();
 }
 ```
 
@@ -136,8 +128,13 @@ Full API docs and guides (auto-generated from source) are available at [API Refe
 
 ## Benchmarks
 
-- See `/benchmarks` in the repo for performance evaluation.
-- Contributors: Update benchmarks and document results for performance-impacting PRs.
+- See [`/benchmarks`](./benchmarks) in the repo for benchmark projects.
+- Run benchmarks with:
+  ```shell
+  dotnet run --project benchmarks/PolylineAlgorithm.Benchmarks --configuration Release
+  ```
+- For guidance on writing and interpreting benchmarks, see [docs/benchmarks.md](./docs/benchmarks.md).
+- Contributors: update benchmarks and document results for performance-impacting PRs.
 
 ## FAQ
 
@@ -173,13 +170,13 @@ A: Currently, only batch encode/decode is supported. For streaming scenarios, im
 
 ## Contributing
 
-- Follow code style and PR instructions in [AGENTS.md](./AGENTS.md).
+- Follow code style and PR instructions in [CONTRIBUTING.md](./CONTRIBUTING.md).
 - Ensure all features are covered by tests and XML doc comments.
 - For questions or suggestions, open an issue and use the provided templates.
 
 ## Support
 
-Have a question, bug, or feature request? [Open an issue!](https://github.com/petesramek/polyline-algorithm-csharp/issues)
+Have a question, bug, or feature request? [Open an issue](https://github.com/petesramek/polyline-algorithm-csharp/issues/new/choose) — bug report and feature request templates are available to guide you.
 
 ---