googlechat: implement typing indicator via message editing

src/config/types.googlechat.ts

@@ -87,6 +87,15 @@ export type GoogleChatAccountConfig = {
   /** Per-action tool gating (default: true for all). */
   actions?: GoogleChatActionConfig;
   dm?: GoogleChatDmConfig;
+  /**
+   * Typing indicator mode (default: "message").
+   * - "none": No indicator
+   * - "message": Send "_<name> is typing..._" then edit with response
+   * - "reaction": React with 👀 to user message, remove on reply
+   *   NOTE: Reaction mode requires user OAuth (not supported with service account auth).
+   *   If configured, falls back to message mode with a warning.
+   */
+  typingIndicator?: "none" | "message" | "reaction";
 };
 
 export type GoogleChatConfig = {

src/config/zod-schema.providers-core.ts

@@ -321,6 +321,7 @@ export const GoogleChatAccountSchema = z
       .strict()
       .optional(),
     dm: GoogleChatDmSchema.optional(),
+    typingIndicator: z.enum(["none", "message", "reaction"]).optional(),
   })
   .strict();