docs(bench): refresh README read + top-N numbers (M5, 80M rows); add writer POM example

Re-ran JavaVsJniReadBenchmark at 80M rows on Apple M5. Single-column read
throughput and top-N tables updated; provenance bumped to the current commit.
Compression table unchanged (deterministic import size, unaffected by recent
changes). Also adds the vortex-writer dependency snippet alongside the write
example, mirroring the reader Quickstart.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: dfa1

README.md

@@ -16,9 +16,9 @@ reference implementation's JNI bindings).
 
 | Column | Type | vortex-java (ops/s) | vortex-jni (ops/s) | Speedup |
 |--------|------|--------------------|-------------------|---------|
-| volume | I64 / bitpacked | 14.2 | 6.7 | **2.1×** |
-| close  | F64 / ALP       | 7.7  | 6.3 | **1.2×** |
-| symbol | Utf8 / varbin   | 11.0 | 1.3 | **8.8×** |
+| volume | I64 / bitpacked | 13.7 | 6.4 | **2.1×** |
+| close  | F64 / ALP       | 8.3  | 6.1 | **1.4×** |
+| symbol | Utf8 / varbin   | 13.6 | 1.2 | **11.8×** |
 
 ops/s = complete file scans per second; higher is better.
 
@@ -31,10 +31,10 @@ ops/s = complete file scans per second; higher is better.
 
 | N rows | vortex-java (ops/s) | vortex-jni (ops/s) | Speedup |
 |--------|--------------------|-------------------|---------|
-| 10     | 2,701       | 550             | **4.9×** |
-| 100    | 2,697       | 573             | **4.7×** |
+| 10     | 2,588       | 882             | **2.9×** |
+| 100    | 2,538       | 887             | **2.9×** |
 
-Measured 2026-06-16, commit `74ec207b`. See [docs/explanation.md](docs/explanation.md#benchmarks) for full tables and methodology.
+Measured 2026-06-25, commit `b78989fa`. See [docs/explanation.md](docs/explanation.md#benchmarks) for full tables and methodology.
 
 **Compression** — NYC Yellow Taxi 2024-01, 2,964,624 rows × 19 columns, imported from the
 same Parquet file (47.6 MB), cascading depth 3, Apple M5:
@@ -95,6 +95,14 @@ try (VortexReader vf = VortexReader.open(Path.of("data/example.vortex"));
 
 ### Minimal write example
 
+```xml
+<dependency>
+  <groupId>io.github.dfa1.vortex</groupId>
+  <artifactId>vortex-writer</artifactId>
+  <version>0.9.0</version>
+</dependency>
+```
+
 ```java
 DType.Struct schema = DType.structBuilder()
         .field("timestamp", DType.I64)