chore(sync): re-base the fork onto upstream dsh-better-sidebar v0.19.1

The fork was pinned at upstream v0.18.0. That is the entire reason the window
ran TWO sidebars and TWO near-identical panel toggles: DSH 2.0.10 ships its own
right sidebar (@deepseek-ai/dsh-client-ui-sidebar-right), and upstream only
adopted it in v0.19.0-alpha.1 — which arrived after our fork point. v0.19.1 is
also the one upstream line whose support range actually matches our host
(engines.dsh >=0.1.5-rc.1, 14 DSH peers ^0.1.5-rc.1, host = 0.1.5-rc.2), so it
is the only tag the host's startup precheck accepts.

What upstream v0.18.0 → v0.19.1 brings
- src/client/native/{index,surface,tab-adapter}.tsx: every tab the plugin can
  draw becomes an OFFICIAL native tab type + body, and an external plugin's
  descriptor registered later gets its native type too. This is what retires
  the fork's own right panel — and with it the duplicate toggle cluster
  (`toggleCluster` is gone from v0.19.1).
- native tab-chip icons via the `sidebar.right.pane.tab.title` seat, coloured
  built-in tab icons, file/folder glyphs from DSH's own `FileTypeIcon`.
- guide descriptions (DSH renders them while the guide lists <= 4 entries),
  tab bodies that fill the panel, and the 0.1.5-rc.2 adaptation work we were
  carrying by hand (peer/devDep pinning, primitives' transitive devDeps).

How the sync was done
Rebuilt the tree from the v0.19.1 tag rather than resolving 53 conflicted
files: our v0.18.0 delta was measured first and is only (a) one mechanical
rename `dsh-better-sidebar` -> `dsh-apes-sidebar` and (b) ten real edits. So:
tag tree + rename (scoped: code/config/scripts/tests/README, while the 46
historical docs/plans records and switch.sh's upstream package name stay
untouched) + re-applied deltas + our apes module.

Fork deltas re-applied on the new base
- src/client/apes/ (icons / locales / tabs): the three apes:* information-layer
  tabs (agents / apps / profile), registered through the same BetterSidebarService
  as the builtins — which is exactly why they now ride upstream's native adapter
  into the official sidebar for free.
- identity: package.json (name/version 1.2.0/description/forkedFrom), dsh.plugin.json
  (id/version), SIDEBAR_SERVICE_VERSION 1.2.0, README fork notice,
  docs/external-plugin-guide.md.
- scripts/switch.sh + the pnpm switch* scripts (apes <-> upstream two-line switch).
- tests/apes-tabs.spec.ts (unescaped: it starts from the v0.19.1 base).

Dropped
- the Phase A native-registration spike (`apes/native-tabs.tsx` + its spec): it
  re-derived by hand exactly what upstream's native layer already does — the
  hand-written bridge is dead weight now, and v0.19.1's own e2e/jsdom lanes
  cover the same seat contract far better.
- the unused apesProfileGuideDesc key and the two package.json.bak.* backups.

Verified on the new base: typecheck clean; build clean; 1351 passed / 9 skipped
(128 files), up from 1255 on the old base.

tsdown.config.ts

@@ -1,15 +1,15 @@
 /**
- * tsdown build for dsh-better-sidebar: the host-half lib (lib/index.js and
+ * tsdown build for dsh-apes-sidebar: the host-half lib (lib/index.js and
  * the lib/invariant.js companion, ESM node) plus the two browser client
  * bundles (lib/client.js and lib/client-registry.js, CJS closure factory) —
  * one per install channel:
  *
  * - `lib/client.js` serves the official profile channel, registering with
- *   the package-name id `dsh-better-sidebar` (the client-modules compose
+ *   the package-name id `dsh-apes-sidebar` (the client-modules compose
  *   keys on the package name; keep it in sync with package.json `name`),
  * - `lib/client-registry.js` serves the plugin-registry channel
  *   (dsh.plugin.json), registering with the manifest id
- *   `dsh-external/dsh-better-sidebar` (the registry browser-side `arrive()`
+ *   `dsh-external/dsh-apes-sidebar` (the registry browser-side `arrive()`
  *   check requires bundle id === plugin id).
  *
  * Both bundles replicate the official DSH client-bundle preset
@@ -119,9 +119,9 @@ function browserSourcePath(source: string, sourcemapPath: string): string {
 /**
  * One client bundle build for a plugin id. The same src/client/index.tsx is
  * compiled twice with only the registered id and the output file name
- * differing: the official channel uses the package name (`dsh-better-sidebar`)
+ * differing: the official channel uses the package name (`dsh-apes-sidebar`)
  * and the registry channel uses the manifest id
- * (`dsh-external/dsh-better-sidebar`).
+ * (`dsh-external/dsh-apes-sidebar`).
  * @param pluginId - the `__ModuleLoader__.load({ id })` value and the
  *   data-plugin style-tag prefix of this bundle.
  * @param entryFile - the output file name under lib/.
@@ -186,7 +186,7 @@ function clientBundle(pluginId: string, entryFile: string): UserConfig {
  * loader (src/client/chunk-loader.ts) materializes it with a require built
  * from the module table's seed words.
  *
- * Chunk css tags use the constant plugin id `dsh-better-sidebar` (matching
+ * Chunk css tags use the constant plugin id `dsh-apes-sidebar` (matching
  * the official channel; the registry channel re-injects an identical copy
  * of the shared module css — same content, no functional impact).
  * @param name - chunk name; entry src/client/chunks/<name>.tsx, output
@@ -216,7 +216,7 @@ function chunkBundle(name: string): UserConfig {
     noExternal: (id: string) => (CLIENT_EXTERNALS.includes(id) ? undefined : true),
     plugins: [
       purityGatePlugin(),
-      makeCssPlugin('dsh-better-sidebar'),
+      makeCssPlugin('dsh-apes-sidebar'),
       ...(name === 'mermaid' ? [mermaidChunkAliases()] : []),
     ],
     outputOptions: {
@@ -341,9 +341,9 @@ export default [
     clean: false,
   },
   // Official profile channel: bundle id = package name (package.json `name`).
-  clientBundle('dsh-better-sidebar', 'client.js'),
+  clientBundle('dsh-apes-sidebar', 'client.js'),
   // Plugin-registry channel: bundle id = manifest id (dsh.plugin.json `id`).
-  clientBundle('dsh-external/dsh-better-sidebar', 'client-registry.js'),
+  clientBundle('dsh-external/dsh-apes-sidebar', 'client-registry.js'),
   // Lazy chunks: shared by both channels, fetched on first use through the
   // plugin's /sidebar/bundle route (see src/client/chunk-loader.ts).
   ...CHUNKS.map(chunkBundle),