feat(search): add @tower/search package with Meilisearch client and helpers

Implements Task 2 of Plan 4 (Archive & Search): provides createMeiliClient,
configureIndex, indexMessage, and deleteMessage for use by the worker and API.

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

packages/search/tsconfig.json

@@ -0,0 +1,8 @@
+{
+  "extends": "../../tsconfig.base.json",
+  "compilerOptions": {
+    "outDir": "./dist",
+    "rootDir": "./src"
+  },
+  "include": ["src"]
+}