Merge pull request #457 from wphillipmoore/feature/456-delete-ci-push

chore(ci): delete ci-push.yml; collapse three-tier CI to two-tier

Author: wphillipmoore

.github/workflows/ci-push.yml

@@ -105,12 +105,13 @@ pre-installed in the dev container images. No local setup required.
 uv sync --group dev
 ```
 
-### Three-Tier CI Model
+### Two-Tier CI Model
 
-Testing is split across three tiers with increasing scope and cost:
+Testing is split across two tiers with increasing scope and cost:
 
 **Tier 1 — Local pre-commit (seconds):** Fast smoke tests in a single
-container. Run before every commit. No MQ, no matrix.
+container. Enforced via the `.githooks` pre-commit gate on every commit.
+No MQ, no matrix.
 
 ```bash
 ./scripts/dev/test.sh        # Unit tests in dev-python:3.14
@@ -119,16 +120,14 @@ container. Run before every commit. No MQ, no matrix.
 ./scripts/dev/audit.sh       # pip-audit in dev-python:3.14
 ```
 
-**Tier 2 — Push CI (~3-5 min):** Triggers automatically on push to
-`feature/**`, `bugfix/**`, `hotfix/**`, `chore/**`. Single Python version
-(3.14), includes integration tests, no security scanners or release gates.
-Workflow: `.github/workflows/ci-push.yml` (calls `ci.yml`).
-
-**Tier 3 — PR CI (~8-10 min):** Triggers on `pull_request`. Full Python
+**Tier 2 — PR CI (~8-10 min):** Triggers on `pull_request`. Full Python
 matrix (3.12, 3.13, 3.14), all integration tests, security scanners (CodeQL,
 Trivy, Semgrep), standards compliance, and release gates. Workflow:
 `.github/workflows/ci.yml`.
 
+Push-CI was retired once `st-validate-local` reached parity with PR-CI.
+See wphillipmoore/standard-actions#176 for the parity audit and rationale.
+
 ### Validation
 
 ```bash