Replace complex modular architecture with simplified single-file implementation

## Major Architecture Changes
- **Single-file implementation**: Consolidated entire codebase into cmd/navigator/main.go (~1700 lines)
- **Minimal dependencies**: Only go-htpasswd and yaml.v3, removed complex internal packages
- **Simplified build**: Single Go file compilation with Makefile support

## New Features
- **Managed processes**: External process management (Redis, Sidekiq, etc.) with auto-restart
- **Dynamic port allocation**: Finds available ports instead of sequential assignment
- **PID file management**: Automatic cleanup of stale PID files before starting processes
- **Graceful shutdown**: Proper SIGINT/SIGTERM handling with complete process cleanup
- **Enhanced static serving**: nginx-style try_files behavior with multiple file extensions

## Configuration Changes
- **YAML-first approach**: Modern YAML configuration with template variable support
- **nginx compatibility**: Deprecated but still supported for backward compatibility
- **Removed Rails generator references**: Users create and maintain their own YAML configs

## Process Management Improvements
- **On-demand Rails apps**: Start when requested, stop after configurable idle timeout
- **External process lifecycle**: Start/stop Redis, Sidekiq, and other services with Navigator
- **Process monitoring**: Auto-restart crashed processes when configured
- **Environment inheritance**: Rails apps inherit parent process environment variables

## Performance Optimizations
- **Direct static file serving**: Bypasses Rails for assets with configurable caching
- **try_files implementation**: Serves public content (studios, regions, docs) without Rails overhead
- **Content-Type detection**: Automatic MIME type setting for various file extensions
- **Public route optimization**: Zero Rails overhead for non-authenticated static content

## GitHub Actions Updates
- **Updated CI workflow**: Tests new single-file build with proper YAML configuration
- **Enhanced release workflow**: Multi-platform binaries with version injection and proper release notes
- **Maintained compatibility**: Same release process with improved binary generation

🤖 Generated with [Claude Code](https://claude.ai/code)

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

Author: rubys

.github/workflows/ci.yml

@@ -42,12 +42,39 @@ jobs:
 
     - name: Test binary
       run: |
-        # Create minimal test environment
-        mkdir -p /tmp/test-rails/config/tenant
-        echo '"2025": {}' > /tmp/test-rails/config/tenant/showcases.yml
+        # Create minimal test environment with YAML configuration
+        mkdir -p /tmp/test-rails/config
+        cat << 'EOF' > /tmp/test-rails/config/navigator.yml
+server:
+  listen: 0  # Use port 0 for testing
+  hostname: localhost
+  public_dir: /tmp/test-rails/public
+
+pools:
+  max_size: 1
+  idle_timeout: 300
+  start_port: 4000
+
+auth:
+  enabled: false
+
+static:
+  directories: []
+  extensions: [html, css, js]
+  try_files:
+    enabled: false
+
+applications:
+  global_env: {}
+  standard_vars: {}
+  tenants: []
+
+managed_processes: []
+EOF
+        mkdir -p /tmp/test-rails/public
 
-        # Test that binary starts and exits cleanly with new CLI syntax
-        timeout 5s ./navigator serve --root /tmp/test-rails --listen :0 || [ $? -eq 124 ]
+        # Test that binary starts and exits cleanly with YAML config
+        timeout 5s ./navigator /tmp/test-rails/config/navigator.yml || [ $? -eq 124 ]
 
   build:
     runs-on: ubuntu-latest

.github/workflows/release.yml

@@ -138,7 +138,7 @@ jobs:
           echo "" >> release_notes.md
           echo "Extract the binary and run:" >> release_notes.md
           echo "\`\`\`bash" >> release_notes.md
-          echo "./navigator serve --root /path/to/your/rails/app" >> release_notes.md
+          echo "./navigator config/navigator.yml" >> release_notes.md
           echo "\`\`\`" >> release_notes.md
         fi