v2 phase 4+5: Discord via Chat SDK, expanded MCP tools, message seq IDs

- Chat SDK bridge + Discord adapter (gateway listener, message routing)
- MCP tools refactored into modular structure: core (send_message, send_file,
  edit_message, add_reaction), scheduling (schedule/list/cancel/pause/resume
  tasks), interactive (ask_user_question, send_card), agents (send_to_agent)
- Message seq IDs: shared integer sequence across messages_in/out so agents
  see small numeric IDs instead of platform snowflakes
- busy_timeout=5000 for session DB (poll loop + MCP server concurrent access)
- Always copy agent-runner source to fix stale cache when non-index files change
- Seed script for Discord testing, e2e test script

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

container/agent-runner/src/db/connection.ts

@@ -8,6 +8,7 @@ export function getSessionDb(): Database.Database {
   if (!_db) {
     _db = new Database(process.env.SESSION_DB_PATH || SESSION_DB_PATH);
     _db.pragma('journal_mode = DELETE');
+    _db.pragma('busy_timeout = 5000');
     _db.pragma('foreign_keys = ON');
   }
   return _db;
@@ -20,6 +21,7 @@ export function initTestSessionDb(): Database.Database {
   _db.exec(`
     CREATE TABLE messages_in (
       id             TEXT PRIMARY KEY,
+      seq            INTEGER UNIQUE,
       kind           TEXT NOT NULL,
       timestamp      TEXT NOT NULL,
       status         TEXT DEFAULT 'pending',
@@ -34,6 +36,7 @@ export function initTestSessionDb(): Database.Database {
     );
     CREATE TABLE messages_out (
       id             TEXT PRIMARY KEY,
+      seq            INTEGER UNIQUE,
       in_reply_to    TEXT,
       timestamp      TEXT NOT NULL,
       delivered      INTEGER DEFAULT 0,