Document intentional error suppressions with comments (gt-zn9m)

All 156 instances of _ = error suppression in non-test code now have
explanatory comments documenting why the error is intentionally ignored.

Categories of intentional suppressions:
- non-fatal: session works without these - tmux environment setup
- non-fatal: theming failure does not affect operation - visual styling
- best-effort cleanup - defer cleanup on failure paths
- best-effort notification - mail/notifications that should not block
- best-effort interrupt - graceful shutdown attempts
- crypto/rand.Read only fails on broken system - random ID generation
- output errors non-actionable - fmt.Fprint to io.Writer

This addresses the silent failure and debugging concerns raised in the
issue by making the intentionality explicit in the code.

Generated with Claude Code https://claude.com/claude-code

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

internal/cmd/crew_status.go

@@ -94,7 +94,7 @@ func runCrewStatus(cmd *cobra.Command, args []string) error {
 			untracked = gitStatus.Untracked
 		}
 
-		// Mail status
+		// Mail status (non-fatal: display defaults to 0 if count fails)
 		mailDir := filepath.Join(w.ClonePath, "mail")
 		mailTotal, mailUnread := 0, 0
 		if _, err := os.Stat(mailDir); err == nil {