fix: correct tool count (596), default English dashboard, clean up stale references

- Tool count corrected: 589→596 (was missing 4 OAuth + 4 system config tools)
- System tools: 17→24 (accurate count of @mcp.tool() functions)
- Dashboard defaults to English; Farsi only via ?lang=fa query param
- Updated across all files: README, CLAUDE.md, CONTRIBUTING, DOCKER_README,
  getting-started, CHANGELOG, endpoints config
- Removed remaining Phase references from server.py startup log
- Tests: 289 passing

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

CONTRIBUTING.md

@@ -119,8 +119,8 @@ Then register in `plugins/__init__.py` and add tests.
 ```
 core/       # Core system (auth, site manager, tool registry, dashboard)
 plugins/    # Plugin system (9 plugins, each with handlers + schemas)
-templates/  # Jinja2 templates (dashboard + OAuth)
-tests/      # Test suite (289 tests)
+core/templates/  # Jinja2 templates (dashboard + OAuth)
+tests/           # Test suite (290 tests)
 scripts/    # Setup & deployment scripts
 docs/       # Documentation
 ```