docs: document daemon process management commands

Update README.md and CLAUDE.md to document new process management:
- Add "Process Management" section with daemon commands
- Update all examples to use `./kvs start/stop/status` instead of `&` and `pkill`
- Document global PID/log directories (~/.kvs/)
- Update cluster setup examples
- Update development workflow
- Add daemon package to project structure

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

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

CLAUDE.md

@@ -10,10 +10,16 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 go build -o kvs .
 
 # Run with default config (auto-generates config.yaml)
-./kvs
+./kvs start config.yaml
 
 # Run with custom config
-./kvs /path/to/config.yaml
+./kvs start /path/to/config.yaml
+
+# Check running instances
+./kvs status
+
+# Stop instance
+./kvs stop config
 
 # Run comprehensive integration tests
 ./integration_test.sh
@@ -25,6 +31,32 @@ go run test_conflict.go data1 data2
 go build -o kvs . && ./integration_test.sh
 ```
 
+### Process Management Commands
+```bash
+# Start as background daemon
+./kvs start <config.yaml>       # .yaml extension optional
+
+# Stop daemon
+./kvs stop <config>             # Graceful SIGTERM shutdown
+
+# Restart daemon
+./kvs restart <config>          # Stop then start
+
+# Show status
+./kvs status                    # All instances
+./kvs status <config>           # Specific instance
+
+# Run in foreground (for debugging)
+./kvs <config.yaml>             # Logs to stdout, blocks terminal
+
+# View daemon logs
+tail -f ~/.kvs/logs/kvs_<config>.yaml.log
+
+# Global state directories
+~/.kvs/pids/                    # PID files (works from any directory)
+~/.kvs/logs/                    # Daemon log files
+```
+
 ### Development Workflow
 ```bash
 # Format and check code
@@ -38,11 +70,25 @@ go mod tidy
 go build .
 
 # Test specific cluster scenarios
-./kvs node1.yaml &  # Terminal 1
-./kvs node2.yaml &  # Terminal 2
+./kvs start node1.yaml
+./kvs start node2.yaml
+
+# Wait for cluster formation
+sleep 5
+
+# Test data operations
 curl -X PUT http://localhost:8081/kv/test/data -H "Content-Type: application/json" -d '{"test":"data"}'
 curl http://localhost:8082/kv/test/data  # Should replicate within ~30 seconds
-pkill kvs
+
+# Check daemon status
+./kvs status
+
+# View logs
+tail -f ~/.kvs/logs/kvs_node1.yaml.log
+
+# Cleanup
+./kvs stop node1
+./kvs stop node2
 ```
 
 ## Architecture Overview
@@ -58,7 +104,8 @@ KVS is a **distributed, eventually consistent key-value store** built around thr
 
 #### Modular Package Design
 - **`auth/`** - Complete JWT authentication system with POSIX-inspired permissions
-- **`cluster/`** - Distributed systems logic (gossip, sync, merkle trees)  
+- **`cluster/`** - Distributed systems logic (gossip, sync, merkle trees)
+- **`daemon/`** - Process management (daemonization, PID files, lifecycle)
 - **`storage/`** - BadgerDB abstraction with compression and revision history
 - **`server/`** - HTTP handlers, routing, and lifecycle management
 - **`features/`** - Utility functions for TTL, rate limiting, tamper logging, backup
@@ -147,9 +194,18 @@ Creates two BadgerDB instances with intentionally conflicting data (same path, s
 - **Bootstrap sync**: Up to 30 days of historical data for new nodes
 
 #### Main Entry Point Flow
-1. `main.go` loads config (auto-generates default if missing)
-2. `server.NewServer()` initializes all subsystems
-3. Graceful shutdown handling with `SIGINT`/`SIGTERM`
-4. All business logic delegated to modular packages
+1. `main.go` parses command-line arguments for subcommands (`start`, `stop`, `status`, `restart`)
+2. For daemon mode: `daemon.Daemonize()` spawns background process and manages PID files
+3. For server mode: loads config (auto-generates default if missing)
+4. `server.NewServer()` initializes all subsystems
+5. Graceful shutdown handling with `SIGINT`/`SIGTERM`
+6. All business logic delegated to modular packages
+
+#### Daemon Architecture
+- **PID Management**: Global PID files stored in `~/.kvs/pids/` for cross-directory access
+- **Logging**: Daemon logs written to `~/.kvs/logs/{config-name}.log`
+- **Process Lifecycle**: Spawns detached process via `exec.Command()` with `Setsid: true`
+- **Config Normalization**: Supports both `node1` and `node1.yaml` formats
+- **Stale PID Detection**: Checks process existence via `Signal(0)` before operations
 
 This architecture enables easy feature addition, comprehensive testing, and reliable operation in distributed environments while maintaining simplicity for single-node deployments.