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>

build.py

@@ -2,7 +2,7 @@
 """build.py — package the echo-memory plugin source into a .plugin artifact.
 
 Zips the CONTENTS of echo-memory.plugin.src/ at the archive root (the layout the plugin
-loader expects: .claude-plugin/plugin.json, commands/, skills/ all at top level), excluding
+loader expects: .claude-plugin/plugin.json, hooks/, skills/ all at top level), excluding
 dev cruft. The version is read from the manifest, so the output is named automatically.
 
 Usage: