feat: major improvements to dev container and MCP sidecars

This commit addresses multiple GitHub issues and adds significant enhancements:

🔧 **Issue #8 - Browser Window Title Fix**
- Updated browser window title from "Antigravity Dev Container" to "Dev Container"
- Changed APP_NAME in Dockerfile and startup script for consistency

🚀 **Issue #30 - PostgreSQL Tuner MCP Sidecar**
- Added PostgreSQL performance tuning MCP sidecar (dog830228/pgtuner_mcp)
- Provides AI assistant with database analysis capabilities:
  - Slow query analysis and optimization suggestions
  - Index recommendations with HypoPG virtual testing
  - Table and index bloat detection
  - Vacuum operation tracking and health scoring
- Requires DATABASE_URI in env secret, optional PGTUNER_EXCLUDE_USERIDS
- Disabled by default, configurable via mcpSidecars.pgtuner.enabled
- Updated CLAUDE.md documentation with full configuration examples

🎭 **Playwright: Centralized Service → Sidecar Conversion**
- Converted Playwright from external service to self-contained sidecar
- Updated .mcp.json endpoint: cluster service → http://localhost:8086/sse
- Added deployment configuration with proper health checks
- Enabled by default for immediate browser automation capabilities
- Higher resource allocation (512Mi memory, 1 CPU) for browser workloads

📚 **Documentation Updates**
- Updated README.md: "Antigravity Dev Container" → "Dev Container"
- Added comprehensive MCP sidecars documentation
- Updated secret keys table with database-uri and pgtuner-exclude-userids
- Added configuration examples for all 6 MCP sidecars:
  - kubernetes-mcp (enabled)
  - flux-mcp (enabled)
  - github-mcp (disabled - archived)
  - homeassistant-mcp (disabled - needs secrets)
  - pgtuner-mcp (disabled - needs DATABASE_URI)
  - playwright-mcp (enabled - browser automation)
- Updated CLAUDE.md with complete sidecar reference table
- Added Helm deployment examples and troubleshooting

🏗️ **Architecture Improvements**
- All MCP sidecars now self-contained within pod
- Consistent SSE transport configuration across all sidecars
- Proper health checks and resource limits for all services
- Simplified deployment with no external service dependencies

Generated with [Claude Code](https://claude.ai/code)
via [Happy](https://happy.engineering)

Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>

Dockerfile

@@ -1,7 +1,7 @@
 FROM jlesage/baseimage-gui:ubuntu-22.04-v4
 
 # Set environment variables
-ENV APP_NAME="Antigravity Dev Container" \
+ENV APP_NAME="Dev Container" \
     KEEP_APP_RUNNING=1 \
     DISPLAY_WIDTH=1920 \
     DISPLAY_HEIGHT=1080 \
@@ -119,4 +119,4 @@ ENV HOME=/config/userdata \
 EXPOSE 5800
 
 # Set app name for baseimage-gui
-RUN set-cont-env APP_NAME "Antigravity"
+RUN set-cont-env APP_NAME "Dev Container"