Enforce a truthful local-first AI/privacy contract

Phase 1 of the improvement plan (PR 3 of the sequence). The docs claimed
"fully offline"/"never talks to the network," but text-intel makes HTTP
requests to a configurable Ollama host that could be remote, with no timeout,
no cancellation, and no size limit; the Windows hook logged raw keystrokes
into capture metadata that could then be sent to that host.

Privacy — raw keystroke capture:
- New capture.captureTypedText setting, default false. With it off, printable
  characters are never buffered in JS and the Windows keyboard hook never even
  emits them across the process boundary (the flag is threaded into the C#).
  Shortcut/navigation detection (Ctrl+T, Enter, …) is unaffected.

AI network hardening (app/text-intel.js):
- Every Ollama call goes through fetchJson with an AbortController deadline
  (ai.timeoutMs, default 60s): a dead endpoint fails fast instead of leaving
  UI actions pending forever.
- Cancellation: in-flight requests are tracked and cancelInflight(guideId)
  aborts them; new ai:cancel IPC + api.ai.cancel are called when the editor
  closes, and shutdown cancels everything.
- Bounded concurrency (2) for AI network work.
- Screenshots are only attached when allowed (ai.attachScreenshots), the model
  is vision-capable, and the image is within ai.maxImageBytes — no more
  unbounded base64-expanded 4K bodies.

Local-first host policy (core/text-intel.js):
- New isLoopbackHost + validateOllamaHost. By default only a loopback Ollama
  endpoint is contacted; a remote host is refused with a clear message unless
  ai.allowRemoteHost is explicitly enabled. Blocked hosts are never contacted.

Honest documentation:
- README, package.json, and the welcome screen drop "fully offline"/"never
  talks to the network"/"Electron is the only dependency" for an accurate
  local-first contract that discloses the optional AI path and the bundled
  Tesseract OCR dependency.
- New docs/PRIVACY.md details exactly what is collected locally and the one
  outbound (opt-in, loopback-by-default) AI feature.

Tests: loopback/remote host matrix, remote-blocked-without-opt-in (and never
contacted), remote-allowed-with-opt-in, request timeout, explicit cancel vs
timeout, typed-text off-by-default vs opted-in, shortcut detection still works,
and a source guard that the C# CHAR emission stays behind the opt-in. 224 unit
tests pass; startup smoke and workflow E2E pass.

Co-Authored-By: Claude Fable 5 <[email protected]>

app/renderer/app.js

@@ -172,7 +172,7 @@ class StepForgeApp {
       el('div.welcome', {},
         el('div.welcome-title', {},
           el('h1', {}, 'StepForge'),
-          el('p.muted', {}, 'Capture, annotate, and export step-by-step guides, fully offline.'),
+          el('p.muted', {}, 'Capture, annotate, and export step-by-step guides. Local-first, no telemetry.'),
         ),
         el('div.welcome-actions', {},
           el('button.welcome-btn.primary', {

app/renderer/editor.js

@@ -151,6 +151,11 @@ class GuideEditor {
 
   setActive(active) {
     this.active = Boolean(active);
+    // Leaving the editor cancels any in-flight AI request for this guide so a
+    // slow response can't resolve against a guide the user has closed.
+    if (!this.active && this.guideId) {
+      api.ai.cancel({ guideId: this.guideId }).catch(() => {});
+    }
   }
 
   setSettings(settings) {