Add backpressure stack for agentic coding quality gates

PostToolUse hooks run after every file edit:
- Backend: ./mvnw compile (Checkstyle Google Style + javac)
- Frontend: vue-tsc --noEmit + oxlint + ESLint

Stop hook runs test suites when source files changed, blocks the
agent on failure and re-engages it to fix the issue. Output is
filtered to [ERROR] lines only for context efficiency.

Static analysis: Checkstyle (validate phase), SpotBugs (verify phase),
ArchUnit (9 hexagonal architecture rules as JUnit tests).

Fail-fast: Surefire skipAfterFailureCount=1, Vitest bail=1.
Test log noise suppressed via logback-test.xml (WARN level),
redirectTestOutputToFile, and trimStackTrace.

Existing Java sources reformatted to Google Style (2-space indent,
import order, Javadoc on public types).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

CLAUDE.md

@@ -66,14 +66,16 @@ These are the non-negotiable principles of this project. Every decision — arch
 
 ### Build Commands
 
-| What | Command |
-|------|---------|
-| Backend test | `cd backend && ./mvnw test` |
-| Backend run | `cd backend && ./mvnw spring-boot:run` |
-| Frontend install | `cd frontend && npm install` |
-| Frontend build | `cd frontend && npm run build` |
-| Frontend test | `cd frontend && npm run test:unit` |
-| Frontend dev | `cd frontend && npm run dev` |
+| What             | Command                                |
+|------------------|----------------------------------------|
+| Backend test     | `cd backend && ./mvnw test`            |
+| Backend run      | `cd backend && ./mvnw spring-boot:run` |
+| Frontend install | `cd frontend && npm install`           |
+| Frontend build   | `cd frontend && npm run build`         |
+| Frontend test    | `cd frontend && npm run test:unit`     |
+| Frontend dev     | `cd frontend && npm run dev`           |
+| Backend checkstyle | `cd backend && ./mvnw checkstyle:check` |
+| Backend full verify | `cd backend && ./mvnw verify`         |
 
 ### Agent Documentation
 
@@ -82,6 +84,17 @@ These are the non-negotiable principles of this project. Every decision — arch
 - Agent test reports (browser verification): `.agent-tests/` (gitignored)
 - Use the `browser-interactive-testing` skill (rodney/showboat) for visual verification — this is an agent tool, not manual work.
 
+### Skills
+
+The following skills are available and should be used for their respective purposes:
+
+| Skill                         | Trigger                                      | Purpose                                                                                                                 |
+|-------------------------------|----------------------------------------------|-------------------------------------------------------------------------------------------------------------------------|
+| `rpi-research`                | Deep codebase investigation needed           | Conducts thorough research and produces a written report. Use for understanding how something works before changing it. |
+| `rpi-plan`                    | Feature, refactor, or bug fix needs planning | Creates detailed, phased implementation plans through interactive research and iteration.                               |
+| `rpi-implement`               | Approved plan ready for execution            | Executes approved implementation plans phase by phase with automated and manual verification.                           |
+| `browser-interactive-testing` | Visual verification of web pages             | Headless Chrome testing via rodney/showboat. Use for screenshots, browser automation, and visual test reports.          |
+
 ### Ralph Loops
 
 - Autonomous work is done via Ralph Loops. See [.claude/rules/ralph-loops.md](.claude/rules/ralph-loops.md) for documentation.