chore(infra): add PR title linting workflow (#1177)

Author: mdrxy

.github/workflows/pr_lint.yml

@@ -0,0 +1,91 @@
+# -----------------------------------------------------------------------------
+# PR Title Lint Workflow
+#
+# Purpose:
+#   Enforces Conventional Commits format for pull request titles to maintain a
+#   clear, consistent, and machine-readable change history across our repository.
+#   This helps with automated changelog generation and semantic versioning.
+#
+# Enforced Commit Message Format (Conventional Commits 1.0.0):
+#   <type>[optional scope]: <description>
+#   [optional body]
+#   [optional footer(s)]
+#
+# Allowed Types:
+#   • feat       — a new feature (MINOR bump)
+#   • fix        — a bug fix (PATCH bump)
+#   • docs       — documentation only changes
+#   • style      — formatting, missing semi-colons, etc.; no code change
+#   • refactor   — code change that neither fixes a bug nor adds a feature
+#   • perf       — code change that improves performance
+#   • test       — adding missing tests or correcting existing tests
+#   • build      — changes that affect the build system or external dependencies
+#   • ci         — continuous integration/configuration changes
+#   • chore      — other changes that don't modify src or test files
+#   • revert     — reverts a previous commit
+#   • release    — prepare a new release
+#
+# Allowed Scopes (optional):
+#   genai, vertex, community, infra
+#
+# Rules & Tips for New Committers:
+#   1. Subject (type) must start with a lowercase letter and, if possible, be
+#      followed by a scope wrapped in parenthesis `(scope)`
+#   2. Breaking changes:
+#        – Append "!" after type/scope (e.g., feat!: drop Node 12 support)
+#        – Or include a footer "BREAKING CHANGE: <details>"
+#   3. Example PR titles:
+#        feat(genai): add multi‐tenant support
+#        fix(vertex): resolve flag parsing error
+#        feat(vertex)!: drop string support for invoke
+#        docs: update API usage examples
+#        docs(community): update API usage examples
+#
+# Resources:
+#   • Conventional Commits spec: https://www.conventionalcommits.org/en/v1.0.0/
+# -----------------------------------------------------------------------------
+
+name: '🏷️ PR Title Lint'
+
+permissions:
+  pull-requests: read
+
+on:
+  pull_request:
+    types: [opened, edited, synchronize]
+
+jobs:
+  # Validates that PR title follows Conventional Commits specification
+  lint-pr-title:
+    name: 'Validate PR Title Format'
+    runs-on: ubuntu-latest
+    steps:
+      - name: '✅ Validate Conventional Commits Format'
+        uses: amannn/action-semantic-pull-request@v6
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        with:
+          types: |
+            feat
+            fix
+            docs
+            style
+            refactor
+            perf
+            test
+            build
+            ci
+            chore
+            revert
+            release
+          scopes: |
+            genai
+            vertex
+            community
+            infra
+          requireScope: false
+          disallowScopes: |
+            release
+            [A-Z]+
+          ignoreLabels: |
+            ignore-lint-pr-title