Review — provider-backed Maestro guards

Good additions. Provider-backed replay guards are exactly the safety net needed to refactor the Maestro layer toward "behave like Maestro, but faster" with confidence, and the optional-tap-miss case (optional: true must not touch the device) is a particularly valuable compat invariant to lock down.

A few things to coordinate before/at merge:

1. Duplicate tests across the stack. Two of these tests are byte-for-byte duplicated in sibling PRs:

   • "coalesces tapOn inputText and pressKey Enter through native paths" is also added in #623.
   • "executes runFlow conditions and retry batches at runtime" is also added in #626.

   Whichever lands second will hit a merge conflict (or, worse, silently produce two identically-named test(...) blocks). Please pick a single home for each — either this umbrella PR owns the guards and #623/#626 drop them, or vice versa.

2. The Enter case doesn't actually guard the #623 convergence. This flow uses tapOn + inputText + pressKey: Enter, which already coalesces to wait+fill on main via the existing Enter path. The new behavior in #623 is coalescing without a trailing Enter. If the intent is to guard the convergence work, add the no-Enter variant here so a regression in optimizeTypedAfterTap is caught.

3. Loose snapshots >= 2/3 assertions are fine as smoke checks, but consider asserting exact counts where the flow is deterministic — it would catch accidental extra round-trips, which matters for the "faster" goal.

Nothing blocking on the test logic itself.

Generated by Claude Code

Addressed in ba3308e:

• Kept the umbrella provider guards in #620; #623/#626 can drop their duplicate copies later.
• Added a provider-backed tapOn + inputText no-Enter guard, and kept a separate Enter-preservation guard with a distinct test name.
• Updated optimizeTypedAfterTap so input-looking tapOn + inputText coalesces to wait + fill without requiring trailing Enter.
• Replaced deterministic provider snapshot >= checks with exact counts.

Validation passed: focused provider integration test, focused Maestro replay-flow unit test, pnpm typecheck, and pnpm format with unrelated formatter churn restored.