chore: overhaul GitHub issue/PR templates, add security policy

.github/ISSUE_TEMPLATE/bug_report.md

@@ -1,8 +1,8 @@
 ---
 name: Bug report
 about: Create a report to help us improve
-title: ''
-labels: ''
+title: '[Bug]: '
+labels: 'bug'
 assignees: ''
 
 ---
@@ -11,28 +11,22 @@ assignees: ''
 A clear and concise description of what the bug is.
 
 **To Reproduce**
-Steps to reproduce the behavior:
-1. Go to '...'
-2. Click on '....'
-3. Scroll down to '....'
-4. See error
+Minimal code snippet that reproduces the issue:
+
+```csharp
+// paste reproduction code here
+```
 
 **Expected behavior**
 A clear and concise description of what you expected to happen.
 
-**Screenshots**
-If applicable, add screenshots to help explain your problem.
-
-**Desktop (please complete the following information):**
- - OS: [e.g. iOS]
- - Browser [e.g. chrome, safari]
- - Version [e.g. 22]
+**Actual behavior**
+A clear and concise description of what actually happens (include exception messages/stack traces if applicable).
 
-**Smartphone (please complete the following information):**
- - Device: [e.g. iPhone6]
- - OS: [e.g. iOS8.1]
- - Browser [e.g. stock browser, safari]
- - Version [e.g. 22]
+**Environment**
+ - Package version: [e.g. 2.1.0]
+ - .NET version: [e.g. net8.0]
+ - OS: [e.g. Windows 11, Ubuntu 24.04]
 
 **Additional context**
 Add any other context about the problem here.

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,5 @@
+blank_issues_enabled: false
+contact_links:
+  - name: Ask a question
+    url: https://github.com/petesramek/polyline-algorithm-csharp/discussions
+    about: Use GitHub Discussions for questions, ideas, or general feedback.

.github/ISSUE_TEMPLATE/feature_request.md

@@ -1,8 +1,8 @@
 ---
 name: Feature request
 about: Suggest an idea for this project
-title: ''
-labels: ''
+title: '[Feature]: '
+labels: 'enhancement'
 assignees: ''
 
 ---

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,18 @@
+## Summary
+
+<!-- Briefly describe what this PR does and why. -->
+
+## Type of change
+
+- [ ] Bug fix
+- [ ] New feature
+- [ ] Breaking change
+- [ ] Documentation / samples only
+
+## Checklist
+
+- [ ] Unit tests added or updated (`/tests`)
+- [ ] Benchmarks added or updated (`/benchmarks`) — if performance-impacting
+- [ ] XML doc comments updated for all public API changes
+- [ ] `dotnet format` run with no issues
+- [ ] README and `/samples` updated — if public API changed

.github/dependabot.yml

@@ -4,11 +4,23 @@ updates:
     directory: "/"
     schedule:
       interval: "weekly"
+    labels:
+      - "dependencies"
+    assignees:
+      - "petesramek"
   - package-ecosystem: "nuget"
     directory: "/"
     schedule:
       interval: "weekly"
+    labels:
+      - "dependencies"
+    assignees:
+      - "petesramek"
   - package-ecosystem: "github-actions"
     directory: "/"
     schedule:
       interval: "weekly"
+    labels:
+      - "dependencies"
+    assignees:
+      - "petesramek"

SECURITY.md

@@ -0,0 +1,23 @@
+# Security Policy
+
+## Supported Versions
+
+| Version | Supported |
+| ------- | --------- |
+| Latest  | ✅        |
+| Older   | ❌        |
+
+Only the latest published version receives security fixes. If you are on an older version, please upgrade.
+
+## Reporting a Vulnerability
+
+**Please do not open a public GitHub issue for security vulnerabilities.**
+
+Report security issues privately via [GitHub Security Advisories](https://github.com/petesramek/polyline-algorithm-csharp/security/advisories/new).
+
+Include:
+- A description of the vulnerability
+- Steps to reproduce or a proof-of-concept
+- Potential impact assessment
+
+You can expect an initial response within 5 business days. Once confirmed, a fix will be prioritized and a patch release issued. You will be credited in the release notes unless you prefer to remain anonymous.