ai smart auto-documentation and text rewrite

- Store captureMetadata (OCR text, window/app/element info) with each
  step at capture time so AI always has the original rich context.
- Add buildCaptureContext() to TextIntelService; capture.js uses it
  instead of buildCaptureTitle() so both title and metadata come from
  one pass.
- generateStepPatch() prefers stored captureMetadata over re-running
  OCR, giving the AI the best possible context when the user clicks
  an AI button later.
- Add autoDoc setting: when enabled every capture (shoot, region, and
  session hotkey/click) is automatically documented by AI. Manual
  captures await AI before returning; session captures fire-and-forget
  and push a step:updated event so the renderer reloads seamlessly.
- Add ai:rewriteText IPC and rewriteText() method for plain-text
  polishing via a separate callOllamaText() that skips JSON mode.
- Add "AI Rewrite" section in the editor right panel: textarea + AI
  button that rewrites whatever the user types in place.
- Improve buildAiPrompt() rules: action-focused title instructions,
  explicit anti-junk rules (no "Capture the screen / OCR" blocks),
  and a context-quality gate that suppresses blocks when context is
  thin.
- Add autoDoc checkbox to AI settings dialog.
- Renderer handles step:updated to reload the selected step after
  background auto-doc finishes.

Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

core/schema.js

@@ -86,6 +86,9 @@ function createStep(fields = {}) {
     codeBlocks: (fields.codeBlocks || []).map((cb) => normalizeCodeBlock(cb, takeOrder(cb))),
     tableBlocks: (fields.tableBlocks || []).map((tb) => normalizeTableBlock(tb, takeOrder(tb))),
     links: fields.links || [], // { id, label, targetStepId }
+    captureMetadata: (fields.captureMetadata && typeof fields.captureMetadata === 'object' && !Array.isArray(fields.captureMetadata))
+      ? { ...fields.captureMetadata }
+      : null,
   };
 }