ci: add semantic PR title workflow

[albert20260301]

Summary

• add the shared semantic PR-title workflow used across Altertable SDK repositories
• validate pull request titles against the Conventional Commit types release-please expects for squash merges

Validation

• python3 content check for the expected workflow trigger, action, and token wiring

Notes

• CI-only change; no package runtime behavior changed

[albert20260301]

@leo-altertable could you review this?

I picked you because the history signal is mostly release bot / previous Albert setup, so the Python stack signal points to you. CI is pending on the new PR. The main review focus is whether this matches the shared release-please PR-title guardrail used by the other SDKs.