ci: simplify github actions workflows

[calmcacil]

Summary

This PR simplifies CI/release workflows to reduce scheduled noise, remove brittle scheduled branch-protection automation, and keep release tagging deterministic.

Key changes

• Reworked CI into filtered static/package jobs with stable required aggregate.
• Replaced external conventional-commit action with shell-based checks.
• Reduced release automation surface and removed unnecessary workflow mutation and manual override paths.

Validation

• bash scripts/check-static.sh
• Workflow YAML parse validation

Notes

• No application code changes were made; this is workflow-only.