feat(gui): dsh-client-hmr reload driver and the dshClient-discovered watch-build script

client-hmr is a normal plugin package composed into dev graphs only. It
listens on /plugins/events and reloads one plugin per rebuilt frame,
serialized: invalidate, prefetch (fresh factory registers while the old
fiber still serves), registry.delete before touching the fiber, drain
disposers, drop owned style tags, entry.refresh(), fiber.await() loud.
Dependency cascade costs zero client code — fiber activation epochs
re-load dependents through cordis itself. Reload is coarse by design;
no rollback in v1; self-reload works with a frame gap the next rebuild
heals.

scripts/dev-web.ts (pnpm run dev:web) is the convenience watch-build:
it discovers its package list by scanning packages/*/*/package.json for
dshClient platform "web" at startup — no hardcoded roster — and talks
no protocol to the host. Gate bookkeeping rides along: knip entries for
the new packages, README model-experience allowlist rows.

package.json

@@ -95,6 +95,7 @@
     "demo:cordis": "node --import tsx packages/examples/tui-demo/src/bin.ts examples/cordis-agent/cordis.yml",
     "demo:acp": "node --import tsx packages/examples/acp-demo/src/bin.ts --config examples/acp-agent/cordis.yml",
     "demo:web": "npm run build && npm run build:web && node --import tsx apps/cli/src/bin.ts web",
+    "dev:web": "tsx scripts/dev-web.ts --poll",
     "postinstall": "node scripts/install-lefthook.mjs"
   },
   "devDependencies": {