chore(claude): improve Claude Code integration

- Add CLAUDE.md importing copilot-instructions.md with Claude Code section
- Add .claude/settings.json with ./mvnw permissions
- Add .claude/commands/precommit.md with full pre-commit checklist
- Replace github.copilot-chat with anthropic.claude-code in extensions.json
- Fix co-author in copilot-instructions.md to Claude Sonnet 4.6
- Add .claude/settings.local.json to .gitignore

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: nanotaboada

.claude/commands/precommit.md

@@ -0,0 +1,7 @@
+Run the pre-commit checklist for this project:
+
+1. Remind me to update `CHANGELOG.md` `[Unreleased]` section (Added / Changed / Fixed / Removed) — I must do this manually.
+2. Run `./mvnw clean install` — must succeed with no compilation warnings and all tests passing.
+3. Remind me to open `target/site/jacoco/index.html` to verify coverage after the build completes.
+
+Run step 2, report the results clearly, then propose a branch name and commit message for my approval using the format `type(scope): description (#issue)` (max 80 chars; types: `feat` `fix` `chore` `docs` `test` `refactor` `ci` `perf`). Do not create the branch or commit until I explicitly confirm.

.claude/settings.json

@@ -0,0 +1,7 @@
+{
+  "permissions": {
+    "allow": [
+      "Bash(./mvnw *)"
+    ]
+  }
+}

.github/copilot-instructions.md

@@ -120,5 +120,5 @@ Example: `feat(api): add player stats endpoint (#42)`
 ```text
 feat(scope): description (#issue)
 
-Co-authored-by: Claude <noreply@anthropic.com>
+Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>
 ```

.gitignore

@@ -1,4 +1,5 @@
 HELP.md
+.claude/settings.local.json
 target/
 !.mvn/wrapper/maven-wrapper.jar
 !**/src/main/**/target/

.vscode/extensions.json

@@ -14,7 +14,7 @@
     "vscjava.vscode-spring-initializr",  // Spring Initializr - Generate Spring Boot projects
 
     // AI Assistance
-    "github.copilot-chat",               // GitHub Copilot Chat - AI-powered coding assistant
+    "anthropic.claude-code",             // Claude Code - AI-powered coding assistant
     "coderabbit.coderabbit-vscode",      // CodeRabbit - AI-powered code review
 
     // Code Quality

CLAUDE.md

@@ -0,0 +1,7 @@
+# CLAUDE.md
+
+@.github/copilot-instructions.md
+
+## Claude Code
+
+- Run `/precommit` to execute the full pre-commit checklist for this project.