feat: migrate runtime from Node.js to Bun

- Replace better-sqlite3 with bun:sqlite (native, no native addon build)
- Change all spawn('node') to spawn('bun') for agent processes
- Update package.json scripts: node→bun, tsx→bun, npm→bun
- Add bun-types for tsc compatibility
- Add bun:sqlite→better-sqlite3 shim for vitest (tests run on Node.js)
- Update Dockerfile: install bun alongside Node.js (CLIs need Node)
- Update setup/platform.ts: getNodePath() resolves bun binary
- Remove better-sqlite3 from production dependencies (devDep only for tests)

package.json

@@ -6,23 +6,22 @@
   "main": "dist/index.js",
   "scripts": {
     "build": "tsc",
-    "build:runners": "npm --prefix runners/agent-runner install && npm --prefix runners/agent-runner run build && npm --prefix runners/codex-runner install && npm --prefix runners/codex-runner run build",
+    "build:runners": "bun install --cwd runners/agent-runner && bun run --cwd runners/agent-runner build && bun install --cwd runners/codex-runner && bun run --cwd runners/codex-runner build",
     "restart:stack": "bash scripts/restart-ejclaw-stack.sh",
-    "restart:hint": "tsx src/restart-context-cli.ts write",
-    "start": "node dist/index.js",
-    "dev": "tsx src/index.ts",
+    "restart:hint": "bun src/restart-context-cli.ts write",
+    "start": "bun dist/index.js",
+    "dev": "bun --watch src/index.ts",
     "typecheck": "tsc --noEmit",
     "format": "prettier --write \"src/**/*.ts\"",
     "format:fix": "prettier --write \"src/**/*.ts\"",
     "format:check": "prettier --check \"src/**/*.ts\"",
     "prepare": "husky",
-    "setup": "tsx setup/index.ts",
+    "setup": "bun setup/index.ts",
     "test": "vitest run",
     "test:watch": "vitest"
   },
   "dependencies": {
     "@modelcontextprotocol/sdk": "^1.27.1",
-    "better-sqlite3": "^11.8.1",
     "cron-parser": "^5.5.0",
     "discord.js": "^14.18.0",
     "pino": "^9.6.0",
@@ -31,12 +30,13 @@
     "zod": "^4.3.6"
   },
   "devDependencies": {
-    "@types/better-sqlite3": "^7.6.12",
+    "@types/better-sqlite3": "^7.6.13",
+    "@types/bun": "^1.3.11",
     "@types/node": "^22.10.0",
     "@vitest/coverage-v8": "^4.0.18",
+    "better-sqlite3": "^12.8.0",
     "husky": "^9.1.7",
     "prettier": "^3.8.1",
-    "tsx": "^4.19.0",
     "typescript": "^5.7.0",
     "vitest": "^4.0.18"
   },