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/molecule_lifecycle.go

@@ -177,7 +177,7 @@ bonded_at: %s
 	opts := beads.InstantiateOptions{Context: ctx}
 	steps, err := b.InstantiateMolecule(proto, child, opts)
 	if err != nil {
-		// Clean up the child container on failure
+		// Clean up the child container on failure (best-effort cleanup)
 		_ = b.Close(child.ID)
 		return fmt.Errorf("instantiating bonded molecule: %w", err)
 	}
@@ -481,7 +481,7 @@ squashed_at: %s
 		return fmt.Errorf("creating digest: %w", err)
 	}
 
-	// Add the digest label
+	// Add the digest label (non-fatal: digest works without label)
 	_ = b.Update(digestIssue.ID, beads.UpdateOptions{
 		AddLabels: []string{"digest"},
 	})