ci: Enforce conventional commit structure for commit messages #1 (cadence-workflow#7278)

<!-- Tell your future self why have you made these changes -->
**Why?**

Our existing commit process:
- doesn't immediately convey when there are breaking changes to the
releaser
- doesn't provide information about how to categorize changes in each
release
- is entirely manual preparing releases
- doesn't always give "good" information about what is contained within
a commit
- doesn't give a good idea of the risk of a given commit 

Furthermore, users have stated that our release notes do not provide
easily discernable information about what is in a release, including:
- if there are breaking changes
- which features are in a given release 
- why they should upgrade

Adding conventional commits aims to tackle these pieces and make
contributing to the repository significantly easier.

This PR adds a linter that will give feedback to developers on their
commit message style, and will eventually enforce conventional commits
for each merge PR.

<!-- How have you verified this change? Tested locally? Added a unit
test? Checked in staging env? -->
**How did you test it?**

Currently testing. 

<!-- Assuming the worst case, what can be broken when deploying this
change to production? -->
**Potential risks**

Adding this GitHub action may have unintended consequences for the
commit process, and should be monitored to ensure that it doesn't
inhibit merging to the repository.

<!-- Is it notable for release? e.g. schema updates, configuration or
data migration required? If so, please mention it, and also update
CHANGELOG.md -->
**Release notes**

N/A

<!-- Is there any documentation updates should be made for config,
https://cadenceworkflow.io/docs/operation-guide/setup/ ? If so, please
open an PR in https://github.com/cadence-workflow/cadence-docs -->
**Documentation Changes**

⚠️ TODO

Author: c-warren

.github/workflows/semantic-pr.yml

@@ -0,0 +1,72 @@
+name: Semantic Pull Request
+
+on:
+  pull_request:
+    types:
+      - opened
+      - edited
+      - synchronize
+
+jobs:
+  semantic-pr:
+    name: Validate PR title follows conventional commit format
+    runs-on: ubuntu-latest
+    # TODO: Remove this once we commit to conventional commits
+    continue-on-error: true
+
+    steps:
+      - name: Validate PR title
+        id: lint_pr_title
+        uses: amannn/action-semantic-pull-request@v5.4.0
+        with:
+          # Allow standard conventional commit types
+          types: |
+            fix
+            feat
+            docs
+            style
+            refactor
+            perf
+            test
+            chore
+            ci
+            build
+          # TODO: Remove this once we've decided on scopes
+          requireScope: false
+          # Skip validation for certain labels if needed
+          ignoreLabels: |
+            skip-commit-format
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Comment on PR if validation fails
+        if: steps.lint_pr_title.outputs.error_message != null
+        uses: actions/github-script@v7
+        with:
+          script: |
+            github.rest.issues.createComment({
+              issue_number: context.issue.number,
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              body: `⚠️ **Semantic PR Check Failed**
+
+              **Error Details:**
+              \`\`\`
+              ${{ steps.lint_pr_title.outputs.error_message }}
+              \`\`\`
+
+              **Required Format:**
+              \`\`\`
+              <type>: <description>
+              \`\`\`
+
+              **Allowed types:** fix, feat, docs, style, refactor, perf, test, chore, ci, build
+
+              **Examples:**
+              - \`feat: add user authentication system\`
+              - \`fix: resolve memory leak in worker pool\`
+              - \`docs: update API documentation\`
+              - \`test: add integration tests for auth flow\`
+
+              This is currently a **warning only** and won't block your PR from being merged.`
+            })