types(shared): add credentials/oauth channels, events, and desktop-api

- Add IPC_CHANNELS entries for credentials list/save/remove/test and
  oauth start/cancel/prompt/manual-code
- Extend DesktopEvent union with oauth:*, credentials-changed, and
  agent-event variants used by pi-mono runtime and settings UI
- Extend DesktopApi CredentialsApi with listCredentials / saveCredential
  / removeCredential / testCredential and OAuth submit helpers

src/shared/contracts/channels.ts

@@ -133,4 +133,14 @@ export const IPC_CHANNELS = {
   windowMaximize: "window:maximize",
   windowClose: "window:close",
   windowIsMaximized: "window:isMaximized",
+  // Credentials (pi-mono)
+  credentialsList: "credentials:list",
+  credentialsSave: "credentials:save",
+  credentialsRemove: "credentials:remove",
+  credentialsTest: "credentials:test",
+  // OAuth (pi-mono)
+  oauthStart: "oauth:start",
+  oauthCancel: "oauth:cancel",
+  oauthPromptResponse: "oauth:submit-prompt",
+  oauthManualCodeResponse: "oauth:submit-manual-code",
 } as const;

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

@@ -1,9 +1,28 @@
 import type { z } from "zod";
 import type { secretInputSchema } from "../schemas-company";
 import type { deleteEntitySchema } from "../schemas-badges";
+import type {
+  CredentialSummary,
+  SaveCredentialInput,
+} from "../schemas-credentials";
+import type {
+  OAuthStartInput,
+  OAuthPromptResponseInput,
+  OAuthManualCodeResponseInput,
+} from "../schemas-oauth";
 import type { DesktopResult } from "./common";
 
 export type CredentialsApi = {
   saveSecret: (input: z.infer<typeof secretInputSchema>) => Promise<DesktopResult<string>>;
   deleteSecret: (input: z.infer<typeof deleteEntitySchema>) => Promise<DesktopResult<boolean>>;
+  // pi-mono credentials
+  listCredentials: () => Promise<DesktopResult<CredentialSummary[]>>;
+  saveCredential: (input: SaveCredentialInput) => Promise<DesktopResult<CredentialSummary>>;
+  removeCredential: (input: { connectorId: string }) => Promise<DesktopResult<boolean>>;
+  testCredential: (input: { connectorId: string }) => Promise<DesktopResult<{ ok: boolean; message: string }>>;
+  // pi-mono OAuth
+  startOAuth: (input: OAuthStartInput) => Promise<DesktopResult<boolean>>;
+  cancelOAuth: (input: { connectorId: string }) => Promise<DesktopResult<boolean>>;
+  submitOAuthPrompt: (input: OAuthPromptResponseInput) => Promise<DesktopResult<boolean>>;
+  submitOAuthManualCode: (input: OAuthManualCodeResponseInput) => Promise<DesktopResult<boolean>>;
 };