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/init.go

@@ -62,7 +62,7 @@ func runInit(cmd *cobra.Command, args []string) error {
 			return fmt.Errorf("creating %s: %w", dir, err)
 		}
 
-		// Create .gitkeep to ensure directory is tracked if needed
+		// Create .gitkeep to ensure directory is tracked if needed (non-fatal)
 		gitkeep := filepath.Join(dirPath, ".gitkeep")
 		if _, err := os.Stat(gitkeep); os.IsNotExist(err) {
 			_ = os.WriteFile(gitkeep, []byte(""), 0644)