refactor: implement unified binary architecture

🏗️ **Major Architecture Refactoring: Separate CLI + Server → Unified Binary**

**Key Changes:**
✅ **Unified Binary**: Single 'insertr' binary with subcommands (enhance, serve)
✅ **Preserved Database Architecture**: Maintained sophisticated sqlc multi-DB setup
✅ **Smart Configuration**: Viper + YAML config with CLI flag precedence
✅ **Updated Build System**: Unified justfile, Air, and npm scripts

**Command Structure:**
- `insertr enhance [input-dir]` - Build-time content injection
- `insertr serve` - HTTP API server (dev + production modes)
- `insertr --config insertr.yaml` - YAML configuration support

**Architecture Benefits:**
- **Shared Database Layer**: Single source of truth for content models
- **Flexible Workflows**: Local DB for dev, remote API for production
- **Simple Deployment**: One binary for all use cases
- **Better UX**: Consistent configuration across build and runtime

**Preserved Features:**
- Multi-database support (SQLite + PostgreSQL)
- sqlc code generation and type safety
- Version control system with rollback
- Professional API endpoints
- Content enhancement pipeline

**Development Workflow:**
- `just dev` - Full-stack development (API server + demo site)
- `just serve` - API server only
- `just enhance` - Build-time content injection
- `air` - Hot reload unified binary

**Migration:** Consolidated insertr-cli/ and insertr-server/ → unified root structure

justfile

@@ -11,7 +11,7 @@ install:
     cd lib && npm install
 
 # Start full-stack development (primary workflow)
-dev: build-lib server-build
+dev: build-lib build
     #!/usr/bin/env bash
     echo "🚀 Starting Full-Stack Insertr Development..."
     echo "================================================"
@@ -34,9 +34,8 @@ dev: build-lib server-build
     
     # Start API server with prefixed output
     echo "🔌 Starting API server (localhost:8080)..."
-    cd insertr-server && ./insertr-server --port 8080 2>&1 | sed 's/^/🔌 [SERVER] /' &
+    ./insertr serve --dev-mode --db ./dev.db 2>&1 | sed 's/^/🔌 [SERVER] /' &
     SERVER_PID=$!
-    cd ..
     
     # Wait for server startup
     echo "⏳ Waiting for API server startup..."
@@ -68,10 +67,10 @@ demo-only:
     npx --prefer-offline live-server demo-site --port=3000 --host=localhost --open=/index.html
 
 # Start development server for about page
-dev-about: build-lib server-build
+dev-about: build-lib build
     #!/usr/bin/env bash
     echo "🚀 Starting full-stack development (about page)..."
-    cd insertr-server && ./insertr-server --port 8080 &
+    ./insertr serve --dev-mode --db ./dev.db &
     SERVER_PID=$!
     sleep 3
     npx --prefer-offline live-server demo-site --port=3000 --host=localhost --open=/about.html
@@ -79,13 +78,13 @@ dev-about: build-lib server-build
 
 # Check project status and validate setup
 check:
-    npm run dev:check
+    npm run check
 
 # Show demo instructions
 demo:
-    npm run dev:demo
+    npm run demo
 
-# Build the entire project (library + CLI)
+# Build the entire project (library + unified binary)
 build:
     npm run build
 
@@ -97,67 +96,61 @@ build-lib:
 watch:
     cd lib && npm run dev
 
-# Start Air hot-reload for Go CLI development
+# Start Air hot-reload for unified binary development
 air:
-    cd insertr-cli && air
+    air
 
-# Build Go CLI only
-build-cli:
-    cd insertr-cli && go build -o insertr
+# Build unified binary only
+build-insertr:
+    go build -o insertr .
 
-# Run CLI help
-cli-help:
-    cd insertr-cli && go run main.go --help
+# Run insertr help
+help:
+    ./insertr --help
 
 # Parse demo site with CLI
 parse:
-    cd insertr-cli && go run main.go parse ../demo-site/
+    ./insertr enhance demo-site/ --output ./dist --mock
 
-# Start CLI development server
-servedev:
-    cd insertr-cli && go run main.go servedev -i ../demo-site -p 3000
+# Enhance demo site (build-time content injection)
+enhance input="demo-site" output="dist":
+    ./insertr enhance {{input}} --output {{output}} --mock
 
 # === Content API Server Commands ===
 
-# Generate Go code from SQL (using sqlc)
-server-generate:
-    cd insertr-server && sqlc generate
-
-# Build the content API server binary
-server-build:
-    cd insertr-server && go build -o insertr-server ./cmd/server
-
 # Start content API server (default port 8080)
-server port="8080":
-    cd insertr-server && ./insertr-server --port {{port}}
+serve port="8080":
+    ./insertr serve --port {{port}} --dev-mode --db ./dev.db
+
+# Start API server in production mode
+serve-prod port="8080" db="./insertr.db":
+    ./insertr serve --port {{port}} --db {{db}}
 
 # Start API server with auto-restart on Go file changes
-server-dev port="8080":
-    cd insertr-server && find . -name "*.go" | entr -r go run ./cmd/server --port {{port}}
+serve-dev port="8080":
+    find . -name "*.go" | entr -r ./insertr serve --port {{port}} --dev-mode --db ./dev.db
 
 # Check API server health
-server-health port="8080":
+health port="8080":
     @echo "🔍 Checking API server health..."
     @curl -s http://localhost:{{port}}/health | jq . || echo "❌ Server not responding at localhost:{{port}}"
 
-# Clean database (development only - removes all content!)
-server-clean-db:
-    @echo "🗑️  Removing development database..."
-    rm -f insertr-server/insertr.db
-    @echo "✅ Database cleaned (will be recreated on next server start)"
-
 # Clean all build artifacts
 clean:
     rm -rf lib/dist
-    rm -rf insertr-cli/insertr
+    rm -rf insertr
+    rm -rf tmp
+    rm -rf dist
     rm -rf node_modules
     rm -rf lib/node_modules
+    rm -f dev.db
+    rm -f insertr.db
 
 # Lint code (placeholder for now)
 lint:
     npm run lint
 
-# Run tests (placeholder for now)
+# Run tests (placeholder for now)  
 test:
     npm run test
 
@@ -167,26 +160,27 @@ dev-setup: install build-lib dev
 # Production workflow: install deps, build everything
 prod-build: install build
 
-
-
 # Show project status
 status:
     @echo "🏗️  Insertr Project Status"
     @echo "========================="
     @echo "📁 Root files:"
-    @ls -la package.json justfile 2>/dev/null || echo "   Missing files"
+    @ls -la package.json justfile go.mod insertr.yaml 2>/dev/null || echo "   Missing files"
     @echo "\n📚 Library files:"
     @ls -la lib/package.json lib/src lib/dist 2>/dev/null || echo "   Missing library components"
-    @echo "\n🔧 CLI files:"
-    @ls -la insertr-cli/main.go insertr-cli/insertr 2>/dev/null || echo "   Missing CLI components"
-    @echo "\n🔌 Server files:"
-    @ls -la insertr-server/cmd insertr-server/insertr-server 2>/dev/null || echo "   Missing server components"
+    @echo "\n🔧 Unified binary:"
+    @ls -la insertr main.go cmd/ internal/ 2>/dev/null || echo "   Missing unified binary components"
     @echo "\n🌐 Demo site:"
     @ls -la demo-site/index.html demo-site/about.html 2>/dev/null || echo "   Missing demo files"
     @echo ""
     @echo "🚀 Development Commands:"
     @echo "   just dev       - Full-stack development (recommended)"
     @echo "   just demo-only - Demo site only (no persistence)"
-    @echo "   just server    - API server only (localhost:8080)" 
+    @echo "   just serve     - API server only (localhost:8080)"
+    @echo "   just enhance   - Build-time content injection"
     @echo ""
-    @echo "🔍 Check server: just server-health"
+    @echo "🔍 Check server: just health"
+
+# Generate sqlc code (for database schema changes)
+sqlc:
+    sqlc generate