2.0.0 — packaging & structure major: skills-only plugin, release-based artifacts

Memory behavior unchanged; the major signals a distribution/install break.

- Legacy commands/ directory DELETED (skills-only; the 1.6.0 skills were verified
  on desktop + CoWork and already took precedence). Pre-skills clients install
  1.6.0 from the release history.
- Artifact policy: the repo tracks only the echo-memory.plugin pointer; the 15
  historical versioned zips leave the tree (git history retains them); versioned
  builds ship as Gitea release assets, one release per v<version> tag, starting
  v2.0.0. .gitignore: *.plugin except the pointer.
- README: post-2.0 repository layout; "packaging for other agent runtimes" note
  (ports are build targets from the canonical tree, never a second source tree).
- ROADMAP-2.0 items ticked; manifest -> 2.0.0.

All suites green (25/25 unit + 4 e2e suites); artifact rebuilt skills-only
(79 entries, no commands/).

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

echo-memory.plugin.src/.claude-plugin/plugin.json

@@ -1,6 +1,6 @@
 {
   "name": "echo-memory",
-  "version": "1.6.0",
+  "version": "2.0.0",
   "homepage": "https://git.alwisp.com/jason/echo",
   "repository": "https://git.alwisp.com/jason/echo",
   "description": "Persistent memory via the ECHO Obsidian vault over the Obsidian Local REST API. Cross-platform Python client: one-call capture/resolve/recall/link/triage over an entity index, hybrid BM25 + graph recall spanning entities + sessions/journal (recency/status-aware), a pre-write duplicate gate, complete-frontmatter capture, session hooks that self-fire load/reflect, offline write-ahead queue, lock-guarded concurrency, linter-enforced routing, and /echo-* commands.",