Fix mail inbox detecting wrong identity from witness/refinery dirs

When GT_ROLE env var is not set, detectSender() now falls back to
cwd-based detection instead of immediately returning "overseer".
This allows running mail commands from witness/refinery directories
without GT_ROLE set (e.g., debugging sessions) and correctly detecting
the identity from the current working directory path.

(gt-od1g)

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

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

internal/cmd/mail.go

@@ -704,10 +704,12 @@ func findLocalBeadsDir() (string, error) {
 // detectSender determines the current context's address.
 // Priority:
 //  1. GT_ROLE env var → use the role-based identity (agent session)
-//  2. No GT_ROLE → return "overseer" (human at terminal)
+//  2. No GT_ROLE → try cwd-based detection (witness/refinery/polecat/crew directories)
+//  3. No match → return "overseer" (human at terminal)
 //
 // All Gas Town agents run in tmux sessions with GT_ROLE set at spawn.
-// Humans in regular terminals won't have GT_ROLE, so they're the overseer.
+// However, cwd-based detection is also tried to support running commands
+// from agent directories without GT_ROLE set (e.g., debugging sessions).
 func detectSender() string {
 	// Check GT_ROLE first (authoritative for agent sessions)
 	role := os.Getenv("GT_ROLE")
@@ -716,8 +718,8 @@ func detectSender() string {
 		return detectSenderFromRole(role)
 	}
 
-	// No GT_ROLE means human at terminal - they're the overseer
-	return "overseer"
+	// No GT_ROLE - try cwd-based detection, defaults to overseer if not in agent directory
+	return detectSenderFromCwd()
 }
 
 // detectSenderFromRole builds an address from the GT_ROLE and related env vars.