feat: writes via chat — Reginald proposes, you approve inline (P4)

Completes "chat is the write-path" (decisions.md D1). Ask Reginald to re-estimate
or reprioritize an issue; it formulates a proposal, you approve it inline, and the
write runs through the same guarded apply_changes engine the Issue screen uses.
The model never writes — it proposes; the app owns approval + execution.

core (@commitea/core):
- propose_change tool declaration + REGINALD_SYSTEM updated ("never claim a change
  is applied; you propose, the human approves").
- proposalsFor(args, currentLabels, title): pure — builds the concrete, non-noop
  ChangeProposal(s) (change + label diff) for a propose_change request, dropping
  invalid/unchanged axes. ChangeProposal / ProposeChangeArgs types.

app:
- model bridge executes propose_change by planning against the issue's current
  labels (no write) and returns the proposals with the turn.
- useChat surfaces pending proposals + approve/dismiss; approve calls onApplyChange
  (AppShell's guarded handler → PUT + board/forecast refetch), dismiss leaves it.
- ChatPanel renders each proposal as a propose-approve card (diff + Approve/Dismiss).

Verified: 101 core tests green (4 proposalsFor added), desktop typecheck clean,
14 fixture e2e green. Gated live e2e against gemma-4-26b: "Set the estimate on #3
to est/5d" → Reginald proposes "est/2d → est/5d" as an inline card, says it's
*proposed* not done; Dismiss leaves the repo untouched. The approve→write path is
the #41 engine (separately verified change→revert).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/desktop/e2e/live-reginald.spec.ts

@@ -30,4 +30,27 @@ test.describe('live Reginald', () => {
 
     await app.close()
   })
+
+  test('proposes an estimate change for inline approval (writes via chat)', async () => {
+    test.skip(!process.env.GITEA_LIVE || !process.env.COMMITEA_MODEL_LIVE, 'live model test — opt-in')
+    test.setTimeout(300_000)
+    const app = await electron.launch({ args: [MAIN], env: { ...process.env } })
+    const win = await app.firstWindow()
+    await win.waitForLoadState('domcontentloaded')
+    await expect(win.getByText(/· local$/)).toBeVisible({ timeout: 20000 })
+
+    const composer = win.getByPlaceholder(/Tell me what to do/)
+    await composer.fill('Set the estimate on issue #3 to est/5d.')
+    await composer.press('Enter')
+
+    // propose_change → an inline propose-approve card (never an auto-write)
+    await expect(win.getByText('Proposed · #3')).toBeVisible({ timeout: 240_000 })
+    await expect(win.getByText(/→ est\/5d/)).toBeVisible()
+    await win.screenshot({ path: join(here, '.artifacts', 'screens', 'live-reginald-propose.png'), fullPage: true, animations: 'disabled' })
+    // Dismiss so the live run never mutates the repo (the write path itself is #41-tested)
+    await win.getByRole('button', { name: 'Dismiss' }).click()
+    await expect(win.getByText(/Left #3 as it was/)).toBeVisible()
+
+    await app.close()
+  })
 })