job6: gsd-pi 2.64.0→3.0.0 — adapt status-reporter parser to ADR-013 cutover

Upgrade confirmed format-incompatible before use (job6 gate, BATCH-2):
gsd-pi 3.0.0 no longer writes .gsd/ROADMAP.md (verified by generating a
real test milestone in a scratch project) — state moved to .gsd/STATE.md,
.gsd/gsd.db (authoritative DB), and one .gsd/milestones/<ID>/<ID>-ROADMAP.md
per milestone, all in a different markdown shape. Every grep/awk in
status-reporter.md PHASE 3 would silently print 0/blank against the old
path instead of erroring.

Rewired PHASE 3 to read `gsd headless query` (stable JSON snapshot, no LLM
call) instead of scraping markdown — smoke-tested against both the absent
case (this repo, no .gsd/) and a real gsd-managed scratch project.

plugins.lock.json pin bumped deliberately to 3.0.0 (update-all.sh honors
the pin; this is the required manual bump).

plugins.lock.json

@@ -7,8 +7,8 @@
   },
   "gsd": {
     "source": "npm:gsd-pi",
-    "version": "2.64.0",
-    "note": "Check latest at https://www.npmjs.com/package/gsd-pi before updating. GSD v2 is a standalone CLI (Pi SDK), not a Claude Code plugin. Run 'gsd' in terminal, not '/gsd' in Claude Code. NOTE: update-all.sh honors this pin — 'make update' will NOT advance gsd past it; bump this version deliberately, then re-run."
+    "version": "3.0.0",
+    "note": "Check latest at https://www.npmjs.com/package/gsd-pi before updating. GSD is a standalone CLI (Pi SDK), not a Claude Code plugin. Run 'gsd' in terminal, not '/gsd' in Claude Code. ADR-013 cutover (3.0.0): DB is authoritative, .gsd/ROADMAP.md no longer exists — read state via 'gsd headless query' (see agents/status-reporter.md PHASE 3), not markdown scraping. NOTE: update-all.sh honors this pin — 'make update' will NOT advance gsd past it; bump this version deliberately, then re-run."
   },
   "gstack": {
     "source": "https://github.com/garrytan/gstack.git",