test: add test infrastructure with CI workflow and image-gen unit tests

docs/testing.md

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+# Testing Strategy
+
+This repository has many scripts, but they do not share a single runtime or dependency graph. The lowest-risk testing strategy is to start from stable Node-based library code, then expand outward to CLI and skill-specific smoke tests.
+
+## Current Baseline
+
+- Root test runner: `node:test`
+- Entry point: `npm test`
+- Coverage command: `npm run test:coverage`
+- CI trigger: GitHub Actions on `push`, `pull_request`, and manual dispatch
+
+This avoids introducing Jest/Vitest across a repo that already mixes plain Node scripts, Bun-based skill packages, vendored code, and browser automation.
+
+## Rollout Plan
+
+### Phase 1: Stable library coverage
+
+Focus on pure functions under `scripts/lib/` first.
+
+- `scripts/lib/release-files.mjs`
+- `scripts/lib/shared-skill-packages.mjs`
+
+Goals:
+
+- Validate file filtering and release packaging rules
+- Catch regressions in package vendoring and dependency rewriting
+- Keep tests deterministic and free of network, Bun, or browser requirements
+
+### Phase 2: Root CLI integration tests
+
+Add temp-directory integration tests for root CLIs that already support dry-run or local-only flows.
+
+- `scripts/sync-shared-skill-packages.mjs`
+- `scripts/publish-skill.mjs --dry-run`
+- `scripts/sync-clawhub.mjs` argument handling and local skill discovery
+
+Goals:
+
+- Assert exit codes and stdout for common flows
+- Cover CLI argument parsing without hitting external services
+
+### Phase 3: Skill script smoke tests
+
+Add opt-in smoke tests for selected `skills/*/scripts/` packages, starting with those that:
+
+- accept local input files
+- have deterministic output
+- do not require authenticated browser sessions
+
+Examples:
+
+- markdown transforms
+- file conversion helpers
+- local content analyzers
+
+Keep browser automation, login flows, and live API publishing scripts outside the default CI path unless they are explicitly mocked.
+
+### Phase 4: Coverage gates
+
+After the stable Node path has enough breadth, add coverage thresholds in CI for the tested root modules.
+
+Recommended order:
+
+1. Start with reporting only
+2. Add line/function thresholds for `scripts/lib/**`
+3. Expand include patterns once skill-level smoke tests are reliable
+
+## Conventions For New Tests
+
+- Prefer temp directories over committed fixtures unless the fixture is reused heavily
+- Test exported functions before testing CLI wrappers
+- Avoid network, browser, and credential dependencies in default CI
+- Keep tests isolated so they can run with plain `node --test`