fix(settings): use the host's @deepseek-ai/schemastery so volatile prefs apply

Every side-card switch was dead: settings.update returned OK and
cordis.patch.yml was written, yet the running plugin never saw the new value
and nothing reported an error.

Root cause: the plugin declared Config with the plain npm `schemastery`
(3.18.0), which has no volatile support. The host resolves plugin config via
`runtime.Config['~standard'].validate()` — i.e. the plugin's OWN schemastery —
so `meta.volatile` nodes were never wrapped in cosmokit volatile references.
`cordis-plugin-loader`'s `_commitVolatile()` bails out as soon as
`volatileEntries(fiber.config)` is empty, so every volatile-only edit was
silently dropped: no in-place update, no plugin restart.

Fix: import z from '@deepseek-ai/schemastery' (peer provided by the host at
mount; pinned 3.18.4 as a devDependency for the dev tree), matching the
repo's existing pnpm-workspace convention for @deepseek-ai/* peers.

Verified: probe reports tabsIsVolatile=true and revision climbing 0->6 across
six writes, each read-back matching the written value (previously the value
was frozen and revision stuck at 1).

Also in this change:
- apes tab ids lose their colon (apes:tasks -> apesTasks, ...): the host's
  settings projection dropped map keys containing a colon.
- sidebar prefs ns follows the profile entry id (`better-sidebar`).
- subagent rows degrade to summary rows when the root catalog never hydrates.
- docs/feedback-0.2.0-rc2-contract-gaps.md: four host contract gaps, gap 4
  documenting the silent volatile-write drop above.

Gates: typecheck 0, lint 0, build 0, test 131 files / 1385 passed.

package.json

@@ -110,6 +110,7 @@
     "@deepseek-ai/dsh-settings": "^0.2.0-rc.2",
     "@deepseek-ai/dsh-subagent": "^0.2.0-rc.2",
     "@deepseek-ai/dsh-tools": "^0.2.0-rc.2",
+    "@deepseek-ai/schemastery": "^3.18.1",
     "@huanlin/dsh-plugin-better-locale": "^0.1.0",
     "react": "^18.2.0",
     "react-dom": "^18.2.0"
@@ -151,7 +152,6 @@
     "node-pty": "^1.1.0",
     "react-icons": "5.7.0",
     "rxjs": "^7.8.2",
-    "schemastery": "^3.18.0",
     "ws": "^8.18.0"
   },
   "devDependencies": {
@@ -182,6 +182,7 @@
     "@deepseek-ai/dsh-util-code-language": "0.2.0-rc.2",
     "@deepseek-ai/dsh-util-time": "0.2.0-rc.2",
     "@deepseek-ai/dsh-util-workspace-path": "0.2.0-rc.2",
+    "@deepseek-ai/schemastery": "3.18.4",
     "@eslint/js": "^10.0.1",
     "@huanlin/dsh-plugin-better-locale": "^0.1.0",
     "@playwright/test": "^1.62.1",