Add automated quality gate workflow

Enables automated quality monitoring with GitHub Actions:
- Auto-creates issues when quality checks fail
- Comments quality metrics on PRs
- Daily security scans (2 AM UTC)
- Prevents merging failing PRs

Quality Gates:
- JaCoCo: ≥93% instruction, ≥86% branch coverage
- SpotBugs: 0 bugs
- PMD: 0 violations
- Checkstyle: 0 errors
- OWASP: 0 critical/high vulnerabilities

Issues auto-labeled: quality-gate, automated, [tool-specific]

See .github/README.md for details.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: Flossy

.github/README.md

@@ -0,0 +1,49 @@
+# GitHub Workflows
+
+## quality-gate.yml
+
+Automated quality monitoring for FlossWare projects.
+
+### What It Does
+
+- ✅ Runs on every push/PR
+- ✅ Executes all Maven quality checks
+- ✅ Comments quality metrics on PRs
+- ✅ Automatically creates issues when quality gates fail:
+  - Code coverage drops below threshold
+  - SpotBugs finds bugs
+  - PMD detects violations
+  - Checkstyle errors
+  - Security vulnerabilities (OWASP)
+- ✅ Daily security scans (2 AM UTC)
+
+### Quality Gates
+
+| Tool | Threshold | Fail Condition |
+|------|-----------|---------------|
+| JaCoCo | 93% instruction, 86% branch | Below threshold |
+| SpotBugs | 0 bugs | Any bugs found |
+| PMD | 0 violations | Any violations |
+| Checkstyle | 0 errors | Any errors |
+| OWASP | 0 critical/high | Critical or high vulnerabilities |
+
+### Issue Labels
+
+Auto-created issues are tagged with:
+- `quality-gate` - All quality gate issues
+- `automated` - Auto-created
+- Specific: `coverage`, `spotbugs`, `pmd`, `checkstyle`, `security`
+
+### Configuration
+
+Edit `quality-gate.yml` to:
+- Adjust coverage thresholds
+- Change schedule
+- Modify issue templates
+- Add custom checks
+
+### Resources
+
+- [Maven Quality Requirements](../build-tools/MAVEN-QUALITY-REQUIREMENTS.md)
+- [Test Coverage Guide](../build-tools/TEST-COVERAGE.md)
+- [FlossWare Build Tools](https://github.com/FlossWare/build-tools)