refactor: prune dead IPC surface and orphaned modules

Drop code that nothing consumed. Verified by full renderer+shared grep:
every removed channel had zero callers via window.agentCompany.* and
zero references from desktop-api types. No backend internal use either —
the database/API-server layers keep their methods, only the IPC exposure
goes.

Removed IPC handlers (26 total):

  Thread CRUD surface (12) — writes happen inside the backend
    createThread, listThreads, addThreadEvent,
    setThreadWaitState, resolveThreadWaitState,
    addParticipant, removeParticipant, listParticipants,
    subscribeThread, unsubscribeThread,
    listSubscriptions, listSubscribedThreads
    (kept reads: getThread, listThreadEvents, listThreadWaitStates)

  Half-implemented features (13)
    saveSecret, listComments, getAgentMetrics, getApiPort,
    listWakeupRequests, listAgentMessages, autoAssignTask,
    listRunEvents, recoveryDismiss,
    getHeartbeatPolicy, setHeartbeatPolicy,
    getRuntimeState, setRuntimeState

  Whole vertical slice: openConnectorAuthTerminal
    IPC handler + channel + preload + DesktopApi type +
    connector-auth-service function + useConnectorCallbacks
    handleLoginConnector + OnboardingContext.onLoginConnector +
    OnboardingWizard wiring. Pi-mono has no CLI auth flow;
    the no-op that "returned false for legacy UI compatibility"
    had no legacy UI left.

Orphaned modules (zero importers in repo):
  src/main/runtime-env.ts
  src/main/database-stale-recovery.ts

Dead schema files (only referenced by their own barrel re-export):
  schemas-participants, schemas-subscriptions, schemas-heartbeat,
  schemas-run-events, schemas-runtime-state, schemas-wakeup

Renderer leftovers:
  .activity-row-enter CSS + its two unreferenced keyframes
  5 orphan i18n keys (app.console, app.refresh, app.expand,
  activity.timeline, auto.trigger) left over from earlier feature
  deletions

Also update two unit tests that mocked openConnectorAuthTerminal in
the RegisterCoreHandlersDependencies pick.

src/shared/contracts/desktop-api/communication.ts

@@ -1,12 +1,11 @@
 import type { z } from "zod";
-import type { AgentMessageRecord, CommentRecord, DocumentRecord, KnowledgeEntryRecord } from "../../types";
-import type { agentMessageInputSchema, commentInputSchema, documentInputSchema, knowledgeEntryInputSchema, listCommentsSchema, markMessageReadSchema, meetingInputSchema, messageQuerySchema, searchMessagesSchema } from "../schemas-messages";
+import type { AgentMessageRecord, DocumentRecord, KnowledgeEntryRecord } from "../../types";
+import type { agentMessageInputSchema, commentInputSchema, documentInputSchema, knowledgeEntryInputSchema, markMessageReadSchema, meetingInputSchema, searchMessagesSchema } from "../schemas-messages";
 import type { deleteEntitySchema } from "../schemas-badges";
 import type { DesktopResult } from "./common";
 
 export type CommunicationApi = {
   addComment: (input: z.infer<typeof commentInputSchema>) => Promise<DesktopResult<string>>;
-  listComments: (input: z.infer<typeof listCommentsSchema>) => Promise<DesktopResult<CommentRecord[]>>;
   saveMeeting: (input: z.infer<typeof meetingInputSchema>) => Promise<DesktopResult<string>>;
   deleteMeeting: (input: z.infer<typeof deleteEntitySchema>) => Promise<DesktopResult<boolean>>;
   saveDocument: (input: z.infer<typeof documentInputSchema>) => Promise<DesktopResult<string>>;
@@ -14,7 +13,6 @@ export type CommunicationApi = {
   saveKnowledgeEntry: (input: z.infer<typeof knowledgeEntryInputSchema>) => Promise<DesktopResult<string>>;
   deleteKnowledgeEntry: (input: z.infer<typeof deleteEntitySchema>) => Promise<DesktopResult<boolean>>;
   sendAgentMessage: (input: z.infer<typeof agentMessageInputSchema>) => Promise<DesktopResult<import("@shared/types").SendMessageResult>>;
-  listAgentMessages: (input: z.infer<typeof messageQuerySchema>) => Promise<DesktopResult<AgentMessageRecord[]>>;
   markMessageRead: (input: z.infer<typeof markMessageReadSchema>) => Promise<DesktopResult<boolean>>;
   searchMessages: (input: z.infer<typeof searchMessagesSchema>) => Promise<DesktopResult<AgentMessageRecord[]>>;
   // Keep reference to silence unused-import checker for DocumentRecord/KnowledgeEntryRecord — consumers infer via schemas.