Promote AgentCompany-New to the repository root and retire the old app

The legacy application - its src, tests, landing site, promo assets, docs,
release tooling, CI workflows, and root configs - leaves the tree; it stays
reachable in history. Everything under AgentCompany-New moves up unchanged:
same package name, so the production userData/database path is untouched,
and e2e/build scripts already resolved paths relative to the project. The
developer cred.txt stays gitignored at its new location. Full verify:ci
passes from the new root.

src/main/database/migrations/005-chat-read-state.ts

@@ -0,0 +1,15 @@
+export const chatReadState = `
+  create table if not exists chat_read_state (
+    org_id text not null references organizations(id) on delete cascade,
+    employee_id text not null references employees(id) on delete cascade,
+    space_id text not null references chat_spaces(id) on delete cascade,
+    last_read_message_id text references chat_messages(id) on delete set null,
+    last_read_at text not null,
+    primary key (employee_id, space_id)
+  );
+
+  create index if not exists idx_chat_read_state_org on chat_read_state(org_id, employee_id);
+
+  insert into schema_migrations(version, name, applied_at)
+  values (5, 'chat_read_state', datetime('now'));
+`;