宜博 / lemonboss

First concrete code commit for DevLoop. Implements all 7 services that
P0.A tools will depend on, per plan-migration P0.0.

Services (server/services/devloop/, ~900 lines):
- path-resolver.js   foundation — resolveProjectRoot + 12 derived paths;
                     sandbox + linked-new mode support; sensitive path
                     blacklist (with /tmp + os.tmpdir() exemptions);
                     ~/.devloop/linked-projects.json registry
- doc-store.js       PRD/SDD multi-file site IO + cheerio validateHTML +
                     validateUnitsSchema + canonical-JSON hashContract
                     + automatic history/ archival
- unit-registry.js   FSM (M-2: pending→coding→testing→passed/failed/blocked);
                     l2GateOpen; diffUnits (added/changed/removed);
                     reset semantics for L2 + L3
- bug-tracker.js     bugs.ndjson append-only + dedupKey + P-9 transition
                     state machine + list/stats/history aggregation
- timeline-logger.js M-13 ProcessTimeline — append/read/tail;
                     summary truncate to 280; payload oversize → ref form
- changelog-writer.js M-15 — append/read/latest for prd/sdd/units revs
- sse-broker.js      per-pid pub/sub + 25s heartbeat + stream.log replay
                     via Last-Event-ID; emit returns monotonic id
- git-vault.js       spawn-git wrapper — init/commit/tag/log/diff/status/
                     resetWorkingTree/revert/archive; per-pid mutex;
                     nothing-to-commit returns {skipped:true} not throw

Tests (server/tests/devloop/, 71 passing):
- path-resolver.test.js  (17 cases) — sensitive path · sandbox alloc · linked-new
- doc-store.test.js      (12 cases) — validateHTML · validateUnitsSchema · hashContract
- unit-registry.test.js  (15 cases) — FSM transitions · l2GateOpen · diffUnits
- bug-tracker.test.js    (10 cases) — open dedup · transition · list filter · history
- timeline-logger.test.js (9 cases) — append/read/tail · summary truncate · oversize
- git-vault.test.js      (8 cases)  — init idempotent · commit · tag · status · archive

vitest config (`globals: true`) means tests use describe/it/expect globally,
no `require('vitest')` needed (and would fail under vitest 4).

Dep added: cheerio@^1.0.0 (used by docStore.validateHTML; HTML parsing).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>