action: dedupe identical reply_to_review_comment calls within a session (#623)

* action: dedupe identical reply_to_review_comment calls within a session

PR #610 reproduced a Kimi K2 stutter where the agent's tool_use surface
showed one `pullfrog_reply_to_review_comment` call but GitHub recorded
two byte-identical POSTs 3s apart, leaving a duplicate response on
`action/mcp/review.ts:14`.

Add `duplicateReplyDecision` (mirrors `duplicateReviewDecision`) and
track per-session replies on `ToolState.reviewReplies`, keyed by
parent `comment_id` + `bodyWithFooter`. Identical re-emissions short
circuit with `{ skipped: true, reason }` instead of POSTing again.
Body-keyed (not just id-keyed) so legitimate follow-up replies with
different content still go through.

Tighten `AddressReviews` step 5 to say *exactly once per comment* and
note that the runtime dedupes identical bodies, so the agent has both
prompt-level guidance and a server-side guarantee.

Co-authored-by: Cursor <cursoragent@cursor.com>

* address review: drop stale file ref in dedupe comment; soften tool description

* remove comment.test.ts

---------

Co-authored-by: Cursor <cursoragent@cursor.com>
Co-authored-by: pullfrog[bot] <226033991+pullfrog[bot]@users.noreply.github.com>

modes.ts

@@ -147,7 +147,7 @@ For simple, well-defined tasks, skip the plan phase and go straight to build.`,
 
 5. Finalize:
    - confirm a clean working tree, then push via \`${t("push_branch")}\` (same push/prepush guidance as Build mode in *SYSTEM*)
-   - reply to each comment using \`${t("reply_to_review_comment")}\`
+   - reply to each comment **exactly once** using \`${t("reply_to_review_comment")}\` — do not re-emit the same call (the runtime dedupes identical bodies and the second call is wasted)
    - resolve addressed threads via \`${t("resolve_review_thread")}\`
    - call \`${t("report_progress")}\` with a brief summary (or the exact push error if push failed)`,
     },