chore(devex): Added stamphog to code

[Gilbert09]

Changes

• Added the stamphog PR approval flow to the code repo - the dev of the mobile app will require fast development on an unreleased product, and so this will help a lot

[greptile-apps]

Prompt To Fix All With AI

Fix the following 2 code review issues. Work through them one at a time, proposing concise fixes.

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### Issue 1 of 2
.github/workflows/pr-approval-agent.yml:68-71
**Missing Python scripts — workflow dead on arrival**

`tools/pr-approval-agent/review_pr.py` does not exist anywhere in this repository (verified against both the PR head and the `master` branch). The workflow always checks out `master` before running, so the `uv run` call here will always exit non-zero with "No such file or directory". The same applies to `tools/pr-approval-agent/dismiss_check.py` in the `decide-delta` job (line 187). Both scripts need to be merged to `master` before this workflow will function.

### Issue 2 of 2
.github/workflows/pr-approval-agent.yml:187
**Same missing-script issue in `decide-delta`**

`tools/pr-approval-agent/dismiss_check.py` is also absent from master. Because `decide-delta` has `set -euo pipefail`, the failure here causes the entire `decide-delta` job to fail, which in turn causes the `review` job's `needs.decide-delta.result == 'failure'` branch to fire — running a review job that then also fails for the same reason.

_{Reviews (1): Last reviewed commit: "Added stamphog to code" | Re-trigger Greptile}