doc(packages): add the host/ and client/ group READMEs and table rows

Both web-GUI groups shipped without the group README that the packages
table names as each group's canonical package/ctx-key map, and without
rows in that table. Adds both bilingual pairs, the two table rows
(ceiling 835→870: two genuinely new product groups joined the canonical
table at minimal row width), and fixes webserver README drift
(WebServerService/ctx.webServer → HttpServerService/ctx.httpServer,
matching src/index.ts).

packages/README.md

@@ -43,6 +43,8 @@ Packages live at `packages/<group>/<pkg>/`; groups are containers, while names r
 | [`sdk/`](sdk/README.md) | Project SDK tooling | Product — stable surface |
 | [`acp/`](acp/README.md) | Automation-only Agent Client Protocol server | Product — stable surface |
 | [`ui/`](ui/README.md) | Human/client integrations: TUI and JSON-RPC, approval/interaction seams, ask-user tool | Product — stable surface |
+| [`host/`](host/README.md) | Web-GUI host half: shared API gateway + HTTP route server | Product — stable surface |
+| [`client/`](client/README.md) | Web-GUI browser half: shell, wire consumer, object services, slot system, `ui-*` feature plugins | Product — stable surface |
 | [`examples/`](examples/README.md) | Demo bundles (agent-spine + TUI/CLI/ACP/JSON-RPC bins) leaves load | Support — example infra |
 | [`support/`](support/README.md) | Support infrastructure (testkits, invariants, replay, Loader smokes) | Support — lower compatibility expectations |
 | [`util/`](util/README.md) | Low-level zero-dependency utilities shared across groups (`Branded<B>`, Harness home/path helpers, timeout, retention) | Support — small, stable, harness-dep-free |