chore(ci): split PR CI from tag release pipeline

[indykish]

Summary

• run CI only on pull requests ()
• run release only on tag pushes ()
• make release workflow self-contained with sequential gates: verify-version -> lint -> test -> cross-compile -> coverage -> create-release -> verify-fetchable
• require pushed tag to match
• simplify Make targets: -> , remove
• update docs (README + ARCHITECTURE) to remove hardcoded versioning and tighten structure

Why

• avoids duplicate CI runs on merge to main
• keeps release deterministic and isolated to tag-driven builds
• keeps docs version-agnostic and easier to maintain

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!