refactor: remove unused bd pin/unpin/hook commands (bd-x0zl)

Analysis found these commands are dead code:
- gt never calls `bd pin` - uses `bd update --status=pinned` instead
- Beads.Pin() wrapper exists but is never called
- bd hook functionality duplicated by gt mol status
- Code comment says "pinned field is cosmetic for bd hook visibility"

Removed:
- cmd/bd/pin.go
- cmd/bd/unpin.go
- cmd/bd/hook.go

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/rpc/client.go

@@ -333,6 +333,11 @@ func (c *Client) Ready(args *ReadyArgs) (*Response, error) {
 	return c.Execute(OpReady, args)
 }
 
+// Blocked gets blocked issues via the daemon
+func (c *Client) Blocked(args *BlockedArgs) (*Response, error) {
+	return c.Execute(OpBlocked, args)
+}
+
 // Stale gets stale issues via the daemon
 func (c *Client) Stale(args *StaleArgs) (*Response, error) {
 	return c.Execute(OpStale, args)