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>

cmd/bd/pour.go

@@ -32,9 +32,9 @@ Use pour for:
   - Anything you might need to reference later
 
 Examples:
-  bd pour mol-feature --var name=auth    # Create persistent mol from proto
-  bd pour mol-release --var version=1.0  # Release workflow
-  bd pour mol-review --var pr=123        # Code review workflow`,
+  bd mol pour mol-feature --var name=auth    # Create persistent mol from proto
+  bd mol pour mol-release --var version=1.0  # Release workflow
+  bd mol pour mol-review --var pr=123        # Code review workflow`,
 	Args: cobra.ExactArgs(1),
 	Run:  runPour,
 }
@@ -260,5 +260,5 @@ func init() {
 	pourCmd.Flags().StringSlice("attach", []string{}, "Proto to attach after spawning (repeatable)")
 	pourCmd.Flags().String("attach-type", types.BondTypeSequential, "Bond type for attachments: sequential, parallel, or conditional")
 
-	rootCmd.AddCommand(pourCmd)
+	molCmd.AddCommand(pourCmd)
 }