fix(boot): Rename session gt-deacon-boot → gt-boot to fix prefix collision

The tmux session name "gt-deacon-boot" was causing HasSession("gt-deacon")
to return true due to tmux prefix matching behavior. This made the daemon
think the Deacon was running when only Boot was active, and caused commands
targeting "gt-deacon" to be sent to Boot session instead.

The fix renames Boot session from "gt-deacon-boot" to "gt-boot", which
has no prefix overlap with "gt-deacon".

Fixes: gt-sgzsb

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

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

internal/cmd/boot.go

@@ -36,7 +36,7 @@ Boot lifecycle:
   4. Boot exits (or handoffs in non-degraded mode)
 
 Location: ~/gt/deacon/dogs/boot/
-Session: gt-deacon-boot`,
+Session: gt-boot`,
 }
 
 var bootStatusCmd = &cobra.Command{