[Workflows] Add Husky pre-commit/pre-push with lint-staged + jest/bats #62

Summary

Add a pre-push Husky hook that runs the Jest and Bats test suites before any push reaches the remote. The pre-commit hook (lint-staged) is already in place — this issue covers the missing push-time gate.

Current State

Both test runners are already configured and available:

• Jest — npm run test:js → jest --config .jest.config.cjs --coverage --forceExit --detectOpenHandles
• Bats — bats is in devDependencies; shell agent specs require .bats test files per the CodeRabbit review instructions

husky and lint-staged are both present in devDependencies and the "prepare": "husky" lifecycle script is wired up.

Work Required

1. Create .husky/pre-push with:

   #!/usr/bin/env sh
   npm run test:js

   Add a Bats step once .bats test files exist (see [Workflows/Agents] Validate imports/includes; add bats/jest smoke tests #63 — adding smoke tests is a related task).

2. Verify the hook is executable — Husky requires the hook file to have execute permissions (chmod +x .husky/pre-push). Confirm the prepare script handles this on fresh installs.

3. Update docs/DEVELOPMENT.md (or equivalent) to document the pre-push behaviour so contributors know pushes will trigger the test suite.

4. Update CONTRIBUTING.md if it describes local setup, to mention that npm ci (which runs prepare → husky) sets up both hooks.

Out of Scope

• Modifying the existing pre-commit hook
• Adding Bats tests themselves (tracked in [Workflows/Agents] Validate imports/includes; add bats/jest smoke tests #63)
• CI workflow changes — the push hook is a local developer experience improvement; CI already runs npm test

Acceptance Criteria

• .husky/pre-push exists and is executable
• Running git push locally triggers npm run test:js and fails the push if tests fail
• Hook is documented in docs/DEVELOPMENT.md or equivalent
• CONTRIBUTING.md local-setup section references the hook
• No regressions to the existing pre-commit hook
• PR uses branch prefix automation/ or fix/

Definition of Ready (DoR)

• Scope is clear and bounded
• Current state documented
• Dependencies identified ([Workflows/Agents] Validate imports/includes; add bats/jest smoke tests #63 for future Bats step)
• Acceptance criteria listed

Definition of Done (DoD)

• All acceptance criteria met
• Hook tested on a clean npm ci install
• Documentation updated
• Approved by maintainer