devops: pre-push hook for typecheck + tests

[nanaf6203-bit]

Summary

Pre-commit runs lint only.

Affected area

• Add a pre-push hook (husky or simple git hook) running typecheck and tests on changed files.

Acceptance criteria

• Implement the change described above.
• Add or update unit/e2e tests locking in the new behaviour.
• Update README / docs to reflect the new state.

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Filed automatically as part of the PropChain code-review sweep.