Phase 0: strip versioned .plugin artifacts + .DS_Store from the tree

Per CHORUS-PLAN.md Phase 0 (and ROADMAP-2.0): versioned build artifacts
no longer live in the tree — future CHORUS versions ship as Gitea
releases. The 14 historical ECHO artifacts (0.6.0–1.5.1) remain
retrievable at the echo-fork-point tag and in the parent jason/echo
repo. Only the current pointer (echo-memory.plugin) stays tracked;
.gitignore updated to enforce this for echo-memory-* and future
chorus-memory-* builds.

Baseline verified green before any conversion work:
- test_echo_client.py 25/25, test_v1_scaffold.py pass
- eval suites (features / offline-queue / patch-semantics / reflect) pass
- run_eval.py: 0 silent write failures, 0 lost/duplicated offline writes

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

.gitignore

@@ -20,8 +20,11 @@ eval/results/*.json
 /echo-memory.config.json
 /dist/
 
-# Per-user BAKED artifacts (build.py --bake-key, named echo-memory-<ver>-<label>.plugin)
-# carry a live vault bearer token — NEVER commit them. They belong in dist/ (above);
-# this also guards any that get built at the repo root. The version-only pointer
-# (echo-memory.plugin) and version-only artifacts (echo-memory-<ver>.plugin) stay tracked.
-echo-memory-*-*.plugin
+# Build artifacts. Per-user BAKED artifacts (build.py --bake-key) carry a live vault
+# bearer token — NEVER commit them; they belong in dist/ (above). As of the CHORUS
+# fork (Phase 0), versioned artifacts are no longer tracked in the tree either —
+# they ship as Gitea releases (per ROADMAP-2.0). Only the current pointer
+# (echo-memory.plugin / chorus-memory.plugin) stays tracked. Historical ECHO
+# artifacts remain at the echo-fork-point tag and in the parent jason/echo repo.
+echo-memory-*.plugin
+chorus-memory-*.plugin