add Gmail contacts autocomplete to compose box (#607)

Adds a gmail:searchContacts IPC channel backed by two indices: a
SENT-label API-backed index (gmail_sent_contacts) for full historical
coverage of people you've actually emailed, and a local-snapshot
fallback (gmail_contacts) used until the SENT sync finishes on first
launch. Both indices warm at startup so the first keystroke in the
recipient box is instant. Renderer wires the suggestions into the
to/cc/bcc fields in email-view with styled chips.

Co-authored-by: arkml <6592213+arkml@users.noreply.github.com>

apps/x/packages/shared/src/ipc.ts

@@ -202,6 +202,21 @@ const ipcSchemas = {
     }),
     res: z.object({}),
   },
+  'gmail:searchContacts': {
+    req: z.object({
+      query: z.string(),
+      limit: z.number().int().positive().optional(),
+      excludeEmails: z.array(z.string()).optional(),
+    }),
+    res: z.object({
+      contacts: z.array(z.object({
+        name: z.string(),
+        email: z.string(),
+        count: z.number(),
+        lastSeenMs: z.number(),
+      })),
+    }),
+  },
   'mcp:listTools': {
     req: z.object({
       serverName: z.string(),