feat(named-agents): sidebar view, synthetic provider, auto-save, snapshot semantics

Implement the frontend of the Named Agents feature (plan §5-§9):
- New features/named-agents module: pure logic (types re-exported from
  @dispatch/wire + transport-contract, validation, provider/model options,
  snapshot helpers, network normalizers, auto-save status model) + an injected
  auto-save controller (name debounce, immediate provider/model save, monotonic
  stale-response guard) + the collapsible sidebar card view.
- Store: /named-agents CRUD + boot seed; selectModel(model, snapshot?) persists
  the raw model WITH the namedAgent snapshot; draft promotion carries it;
  refreshModel restores ModelResponse.namedAgent.
- Chat store setNamedAgent (sends namedAgent on chat.send); Tab.snapshot +
  setSnapshot (retained across rename/remove, persisted with tabs).
- Model selector: synthetic Named Agents provider ALWAYS first; selecting one
  resolves to the raw model + records a snapshot; a retained snapshot of a
  renamed/removed agent still displays as unavailable (plan §7).
- Composition root wires the view (viewKinds + loaded-modules manifest) + feeds
  the selector.

Tests: logic + controller + selector + app-store CRUD (1246 pass), typecheck 0,
biome clean (only pre-existing config infos pending a future migrate), build OK.

1 files changed, 7 insertions, 0 deletions

diff --git a/src/features/chat/index.ts b/src/features/chat/index.ts
index 8cf776b..6de8164 100644
--- a/src/features/chat/index.ts
+++ b/src/features/chat/index.ts
@@ -6,12 +6,19 @@ export type {
 } from "../../core/chunks";
 export { groupRenderedChunks, resolveImageUrl, viewProviderRetry } from "../../core/chunks";
 export type { TurnMetricsEntry } from "../../core/metrics";
+export type { NamedAgentLike, NamedAgentSnapshotLike } from "./model-select";
 export {
+  isNamedAgentSelection,
   isNumberedOpenCode,
   isVisionModel,
   migrateLegacyModelName,
   modelKeyLabel,
+  NAMED_AGENTS_PROVIDER,
+  namedAgentNames,
+  namedAgentSelectionLabel,
+  namedAgentsProviderLabel,
   openCodeNumber,
+  providerKeysWithNamedAgents,
 } from "./model-select";
 export type { ChatTransport, HistorySync, HistoryWindow, MetricsSync } from "./ports";
 export type {