refactor(api,client)!: delete the activity plane; one job roster with record observation

packages/activity/* and packages/api/activity-controller are removed. The
web roster is the session control stream's jobs frames alone; per-job output
observation rides session.observeJob and the client ctx.jobOutput service.
ui-activity returns to its upstream name ui-jobs and renders the single
roster — a row is expandable exactly when its job declared a record
(outputTotal present). Composition rows, dependency-policy exemptions,
tsconfig aliases and references, generated catalogs, and the docs pages
follow; the activity subsystem page is deleted and the jobs page gains the
record contract. The superseding Agent Note records the decision and points
the three prior notes at it.

python/sdk-runtime/package.json

@@ -13,7 +13,6 @@
     "@deepseek-ai/cosmokit": "workspace:^",
     "@deepseek-ai/dsh": "workspace:^",
     "@deepseek-ai/dsh-acp": "workspace:^",
-    "@deepseek-ai/dsh-activity": "workspace:^",
     "@deepseek-ai/dsh-agent": "workspace:^",
     "@deepseek-ai/dsh-agent-instructions": "workspace:^",
     "@deepseek-ai/dsh-agent-loop": "workspace:^",