Track and expose component error/warning counts

[piotrski]

Problem

The React DevTools protocol sends UPDATE_ERRORS_OR_WARNINGS operations (op type 5) with per-component error and warning counts. We parse and skip them at component-tree.ts:242:

case TREE_OPERATION_UPDATE_ERRORS_OR_WARNINGS: {
  // id, numErrors, numWarnings
  i += 4;
  break;
}

This is high-signal data for AI agents — "find the component with errors" is a very common debugging starting point.

Proposed solution

1. Store error/warning counts on ComponentNode (add errors: number and warnings: number fields)
2. Update the TREE_OPERATION_UPDATE_ERRORS_OR_WARNINGS handler to write the counts
3. Add a CLI command: errors — list components with non-zero error or warning counts
4. Include error/warning counts in get component output when non-zero
5. Optionally annotate the tree output (e.g., @c5 [fn] "Form" ⚠2 ✗1)

IPC additions

• New command: { type: 'errors' } — returns components with errors/warnings
• Update get-component response to include counts when non-zero

Files to change

• src/types.ts — add errors/warnings to ComponentNode, add IPC command
• src/component-tree.ts — store counts in the operation handler
• src/daemon.ts — handle new IPC command
• src/cli.ts — add errors command
• src/formatters.ts — format error/warning output, annotate component/tree display
• src/__tests__/component-tree.test.ts — test operation parsing