fix(auto-review): persist pending git action so review cards can't strand

[TyroneNel]

A card's armed auto-review state lives in browser memory. Reload the tab, close it, or switch project between sending the commit prompt and the commit landing, and the only record that a git action was requested is gone. The commit can succeed and the card still sits in review until someone trashes it by hand.

Fixes #365.

The fix

One optional additive field on the board card, pendingGitAction. Existing board.json files parse unchanged; there is no migration.

export const runtimeTaskPendingGitActionSchema = z.object({
  action: runtimeTaskAutoReviewModeSchema,
  requestedAt: z.number(),
  headCommitAtRequest: z.string().nullable(),
  attempt: z.number().int().nonnegative().default(0),
});

• Written when auto-review triggers a git action, capturing the workspace headCommit at that moment.
• Completed on evidence, not absence: the action succeeds when HEAD differs from headCommitAtRequest. changedFiles === 0 with an unchanged HEAD does not advance the card.
• Guarded: a second git action is refused while pendingGitAction is non-null and recent. The state is on the card, so this is a cross-tab lock.
• Bounded: after 15 minutes the pending action is cleared and the user is warned, rather than the card staying armed forever.

The staleness constant and helper live in src/core/task-board-mutations.ts, not api-contract.ts. web-ui consumes the contract type-only; a value import would pull zod into the SPA bundle.

This is the base of a stack. #615 builds on it and moves the actor from the browser into the runtime. This PR is complete on its own: it fixes #365 whether or not #615 lands.

Tests

New tests in web-ui/src/hooks/use-review-auto-actions.test.tsx (remount survival / #365 regression, no-advance on clean tree with unchanged HEAD, second action refused, legacy board hydration, staleness) and schema parse tests in test/runtime/api-validation.test.ts.

Revert-and-rerun proof that the new tests fail without the source change:

$ <revert implementation sources to origin/main>
$ npm --prefix web-ui run test -- src/hooks/use-review-auto-actions.test.tsx
 Test Files  1 failed (1)
      Tests  4 failed | 2 passed (6)
   × persists the pending git action when arming and advances the card after remount once HEAD moves (issue #365)
   × refuses to start a second git action while a recent pending action is armed
   × clears a stale pending git action instead of leaving the card armed forever
   × parses legacy boards without pendingGitAction and keeps valid pendingGitAction values

$ <restore>
$ npm --prefix web-ui run test -- src/hooks/use-review-auto-actions.test.tsx
 Test Files  1 passed (1)
      Tests  6 passed (6)

npm run check, npm run build, npm run web:typecheck and npm run web:test pass.

[greptile-apps]

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