feat(daemon): add auto_pull config parameter for periodic remote sync

Add --auto-pull flag to control whether the daemon periodically pulls from
remote to check for updates from other clones.

Configuration precedence:
1. --auto-pull CLI flag (highest)
2. BEADS_AUTO_PULL environment variable
3. daemon.auto_pull in database config
4. Default: true when sync.branch is configured

When auto_pull is enabled, the daemon creates a remoteSyncTicker that
periodically calls doAutoImport() to pull remote changes. When disabled,
users must manually run 'git pull' to sync remote changes.

Changes:
- cmd/bd/daemon.go: Add --auto-pull flag and config reading logic
- cmd/bd/daemon_event_loop.go: Gate remoteSyncTicker on autoPull parameter
- cmd/bd/daemon_lifecycle.go: Add auto-pull to status output and spawn args
- internal/rpc/protocol.go: Add AutoPull field to StatusResponse
- internal/rpc/server_core.go: Add autoPull to Server struct and SetConfig
- internal/rpc/server_routing_validation_diagnostics.go: Include in status
- Tests updated to pass autoPull parameter

Closes #TBD

internal/rpc/protocol.go

@@ -300,6 +300,7 @@ type StatusResponse struct {
 	// Daemon configuration
 	AutoCommit   bool   `json:"auto_commit"`            // Whether auto-commit is enabled
 	AutoPush     bool   `json:"auto_push"`              // Whether auto-push is enabled
+	AutoPull     bool   `json:"auto_pull"`              // Whether auto-pull is enabled (periodic remote sync)
 	LocalMode    bool   `json:"local_mode"`             // Whether running in local-only mode (no git)
 	SyncInterval string `json:"sync_interval"`          // Sync interval (e.g., "5s")
 	DaemonMode   string `json:"daemon_mode"`            // Sync mode: "poll" or "events"