fix: refactor AGENTS.md into progressive-disclosure structure (#184)

- Root AGENTS.md: 350+ lines → 68 lines (map, not encyclopedia)
- New docs/dev-environment.md (67 lines): Docker, dev.sh, ports, pitfalls
- New docs/ci-pipeline.md (73 lines): Woodpecker setup, monitoring, debugging
- New docs/testing.md (41 lines): Foundry, E2E, version validation
- New docs/codeberg-api.md (32 lines): .netrc auth, API usage
- Updated stale model refs in .claude-code-supervisor.yml files
- Sub-component AGENTS.md files unchanged
- Context docs (PRODUCT-TRUTH, ARCHITECTURE, UX-DECISIONS) unchanged

docs/testing.md

@@ -0,0 +1,41 @@
+# Testing
+
+## Contract Tests (Foundry)
+Run inside `onchain/`:
+```bash
+forge build      # compile contracts
+forge test       # run unit + fork tests
+forge snapshot   # gas snapshot
+```
+
+## Fuzzing
+Scripts under `onchain/analysis/` generate replayable scenarios:
+```bash
+./analysis/run-fuzzing.sh [optimizer] debugCSV
+```
+
+## Integration Testing
+After the stack boots via `dev.sh`:
+- Anvil logs: check for revert errors
+- Ponder GraphQL: `http://localhost:8081/api/graphql`
+- txnBot health: `http://localhost:8081/api/txn/status`
+
+## E2E Tests (Playwright)
+Full-stack tests in `tests/e2e/` verify complete user journeys (mint ETH → swap KRK → stake).
+
+```bash
+npm run test:e2e   # from repo root
+```
+
+- Tests use a mocked wallet provider with Anvil accounts.
+- In CI, the Woodpecker `e2e.yml` pipeline runs these against pre-built service images.
+- See [docs/ci-pipeline.md](ci-pipeline.md) for CI-specific E2E details.
+
+## Version Validation System
+The stack enforces version compatibility across contracts, indexer, and frontend:
+
+- **Contract VERSION**: `Kraiken.sol` exposes a `VERSION` constant (currently v2) that must be incremented for breaking changes to TAX_RATES, events, or core data structures.
+- **Ponder Validation**: On startup, Ponder reads the contract VERSION and validates against `COMPATIBLE_CONTRACT_VERSIONS` in `kraiken-lib/src/version.ts`. Fails hard (exit 1) on mismatch to prevent indexing wrong data.
+- **Frontend Check**: Web-app validates `KRAIKEN_LIB_VERSION` at runtime (currently placeholder; future: query Ponder GraphQL for full 3-way validation).
+- **CI Enforcement**: Woodpecker `release.yml` pipeline validates that contract VERSION matches `COMPATIBLE_CONTRACT_VERSIONS` before release.
+- See `VERSION_VALIDATION.md` (repo root) for complete architecture, workflows, and troubleshooting.