1.6.0 — skills-format migration, lint retired-path fix, plugin.json completeness

Skills migration: each of the eight slash commands gains a skills/<name>/SKILL.md
twin (same invocation name, byte-identical body). Per-skill allowed-tools
pre-authorize the resolved python3/python/py -3 invocations + the CoWork ls
fallback probe; disable-model-invocation: true makes /echo-sweep and /echo-triage
operator-only. Docs-confirmed: a same-name skill takes precedence over the legacy
command, so commands/ coexists until its scheduled 2.0 deletion. The $ECHO
path-resolution dedupe is resolved as not-supported (skill dirs are
self-contained; no cross-skill snippet sharing).

Lint fix: vault_lint.py checks retired patterns BEFORE routes, so a seed README
inside a retired tree (archive/...) flags retired-path instead of being absolved
by the permissive leaf-readme route. New end-to-end regression test seeds
archive/notes/README.md (fails pre-fix, passes now).

plugin.json: version 1.6.0, homepage + repository -> git.alwisp.com/jason/echo.

All suites green: 25/25 client unit tests (incl. routing-sync guard), feature,
reflect, offline-queue, PATCH-semantics. Artifact rebuilt (87 entries, both
formats); pointer refreshed.

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

echo-memory.plugin.src/skills/echo-recall/SKILL.md

@@ -0,0 +1,23 @@
+---
+name: echo-recall
+description: Recall a topic from ECHO memory — matching notes plus their linked neighbourhood
+argument-hint: "[topic, person, or project]"
+allowed-tools: Bash(python3 *echo.py*), Bash(python *echo.py*), Bash(py -3 *echo.py*), Bash(ls /sessions/*)
+---
+
+Use the **echo-memory** skill to recall context for:
+
+> $ARGUMENTS
+
+Run the one-call recall — it resolves the term against the entity index, searches, and expands one hop along `## Related` links and `source_notes`, so you get the connected web (linked decisions, people, prior sessions), not an isolated note:
+
+```bash
+ECHO="${CLAUDE_PLUGIN_ROOT}/skills/echo-memory/scripts/echo.py"
+[ -f "$ECHO" ] || ECHO=$(ls /sessions/*/mnt/.remote-plugins/*/skills/echo-memory/scripts/echo.py 2>/dev/null | head -1)   # CoWork sandbox fallback
+python3 "$ECHO" recall "$ARGUMENTS"
+# Windows: use `python` or `py -3` if `python3` is not on PATH.
+```
+
+The corpus spans the entity graph **plus session logs and journal notes**, ranked by relevance × freshness × status — each hit shows its `updated:`/`status:`, so prefer fresh/active hits and treat stale ones as history. Add `--json` for structured hits (`path/score/type/updated/status/excerpt`) when you need to act on the results programmatically.
+
+Then answer from the assembled context. If you only need the canonical path for one entity, use `echo.py resolve "<title>"` instead. Don't narrate the retrieval.