feat(review_ui): add per-card retry limit with optional backoff in start_review_flow [post-F82]

[ImmortalDemonGod]

What

The F82 fix bounds the infinite retry loop by calling manager.skip_card() on submit_review exception, so a persistently-failing card no longer blocks the session. However, the current behaviour silently skips a card on the first failure — no retry is attempted for transient errors (e.g., momentary DB contention). A per-card retry budget (e.g., max N attempts with optional backoff) would allow transient errors to recover while still bounding the loop.

Why deferred

Explicitly classified as nice-to-have / architectural policy decision in both .aiv/plans/c2-f82-plan.md §6 OUT OF SCOPE and the PR completion contract's OUT-OF-SCOPE REMINDERS:

"Retry-with-backoff or per-card retry budget — architectural policy; open a new issue if desired. Not part of this PR."

The F82 correctness fix (bounded loop + failure signal) was the primary deliverable. Retry policy requires separate design decisions (max retries, backoff strategy, error classification: transient vs. permanent) beyond the scope of the infinite-loop fix.

Acceptance criteria

• start_review_flow respects a configurable per-card retry limit (e.g., via a parameter or project config)
• Transient errors trigger a retry up to the limit; persistent errors cause the card to be skipped via skip_card after exhausting retries
• The loop remains bounded: total iterations ≤ len(review_queue) × max_retries + len(review_queue)
• Tests cover: retry exhaustion (all retries fail → card skipped), success-after-retry (first attempt fails, second succeeds), and zero-retry budget (current single-attempt behaviour)
• The failure-signal semantics (return False only on total failure) are preserved