feat: per-group queue, SQLite state, graceful shutdown

Add per-group container locking with global concurrency limit to prevent
concurrent containers for the same group (#89) and cap total containers.
Fix message batching bug where lastAgentTimestamp advanced to trigger
message instead of latest in batch, causing redundant re-processing.
Move router state, sessions, and registered groups from JSON files to
SQLite with automatic one-time migration. Add SIGTERM/SIGINT handlers
with graceful shutdown (SIGTERM -> grace period -> SIGKILL). Add startup
recovery for messages missed during crash. Remove dead code: utils.ts,
Session type, isScheduledTask flag, ContainerConfig.env, getTaskRunLogs,
GroupQueue.isActive.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/container-runner.ts

@@ -2,7 +2,7 @@
  * Container Runner for NanoClaw
  * Spawns agent execution in Apple Container and handles IPC
  */
-import { exec, spawn } from 'child_process';
+import { ChildProcess, exec, spawn } from 'child_process';
 import fs from 'fs';
 import os from 'os';
 import path from 'path';
@@ -38,7 +38,6 @@ export interface ContainerInput {
   groupFolder: string;
   chatJid: string;
   isMain: boolean;
-  isScheduledTask?: boolean;
 }
 
 export interface ContainerOutput {
@@ -51,7 +50,7 @@ export interface ContainerOutput {
 interface VolumeMount {
   hostPath: string;
   containerPath: string;
-  readonly?: boolean;
+  readonly: boolean;
 }
 
 function buildVolumeMounts(
@@ -185,6 +184,7 @@ function buildContainerArgs(mounts: VolumeMount[], containerName: string): strin
 export async function runContainerAgent(
   group: RegisteredGroup,
   input: ContainerInput,
+  onProcess: (proc: ChildProcess) => void,
 ): Promise<ContainerOutput> {
   const startTime = Date.now();
 
@@ -227,6 +227,8 @@ export async function runContainerAgent(
       stdio: ['pipe', 'pipe', 'pipe'],
     });
 
+    onProcess(container);
+
     let stdout = '';
     let stderr = '';
     let stdoutTruncated = false;