Move Claude workflow concurrency to job level so PR chatter can't cancel queued runs (#21498)

## Problem

A second `@claude` request on a PR while a Claude run is already in
progress gets silently cancelled. Concrete case on #21443: [this
comment](https://github.com/twentyhq/twenty/pull/21443#discussion_r3404037004)
("@claude please investigate and report", 14:24:28) produced [a
run](https://github.com/twentyhq/twenty/actions/runs/27421867558) that
was cancelled 3 seconds after creation, while [the run for an earlier
comment](https://github.com/twentyhq/twenty/actions/runs/27421856742)
was still in progress. Claude never responded.

## Root cause

The `concurrency` block is declared at the **workflow** level, keyed on
the PR number. Two GitHub Actions behaviors combine badly here:

1. A concurrency group holds at most one running + **one pending** run;
every new run entering the group cancels the previously pending one
(`cancel-in-progress: false` only protects the *running* run).
2. Workflow-level concurrency is acquired **before** job-level `if`
conditions are evaluated — so every `issue_comment` /
`pull_request_review_comment` / `pull_request_review` event on the PR
enters the group, even ones with no `@claude` that end up skipped.

So while a Claude run is in progress, any PR activity evicts the queued
`@claude` run. It's even self-defeating: a review-thread reply fires
*two* webhook events (`pull_request_review_comment` + a companion
`pull_request_review` with an empty body), so the companion event
cancels the queued comment run ~2s later. Claude's own "finished" reply
also fires events that kill whatever is queued.

## Fix

Move concurrency to the **job** level. A job whose `if` evaluates false
is skipped before it ever requests the concurrency slot, so only genuine
`@claude` jobs enter the queue. Real Claude runs on the same PR are
still serialized (no parallel pushes to the same branch).

Also gives `claude-cross-repo` its own group keyed on source repo +
issue number — previously a cross-repo dispatch for issue N shared a
group with PR N in this repo and they could needlessly queue behind each
other.

## Remaining limitation

GitHub keeps only one pending job per group: posting three `@claude`
requests while the first is still running will still cancel the second
when the third arrives. Zero-loss queueing would require a unique group
per comment, which would allow concurrent runs pushing to the same PR
branch — not worth it.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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.github/workflows/claude.yml

@@ -14,10 +14,6 @@ on:
 
 permissions: {}
 
-concurrency:
-  group: ${{ github.workflow }}-${{ github.event.issue.number || github.event.pull_request.number || github.event.client_payload.issue_number }}
-  cancel-in-progress: false
-
 jobs:
   claude:
     if: |
@@ -45,6 +41,11 @@ jobs:
         (contains(github.event.issue.body, '@claude') || contains(github.event.issue.title, '@claude')) &&
         contains(fromJson('["OWNER","MEMBER","COLLABORATOR"]'), github.event.issue.author_association)
       )
+    # Job-level (not workflow-level) concurrency: skipped jobs never enter the
+    # group, so PR chatter without @claude can't evict a queued Claude run.
+    concurrency:
+      group: claude-code-${{ github.event.issue.number || github.event.pull_request.number }}
+      cancel-in-progress: false
     runs-on: ubuntu-latest
     timeout-minutes: 60
     permissions:
@@ -118,6 +119,9 @@ jobs:
 
   claude-cross-repo:
     if: github.event_name == 'repository_dispatch'
+    concurrency:
+      group: claude-cross-repo-${{ github.event.client_payload.repo_full_name }}-${{ github.event.client_payload.issue_number }}
+      cancel-in-progress: false
     runs-on: ubuntu-latest
     timeout-minutes: 60
     permissions: