add vault-aware tools: list_vault_tags, check_wikilinks, search_notes

Shared read-only implementations in src/vault/noteTools.ts, exposed to
both backends: as an in-process SDK MCP server (mcp__vault__*, stripped
to plain names in SSE events) for claude-sdk, and as chat-completions
tool defs for openai-compat. Wikilink resolution follows Obsidian
semantics incl. path-links resolved relative to the linking file's
folder; tags come from frontmatter (list + array forms) and inline
#tags, excluding code fences. zod added as a direct dependency
(pinned to the SDK's transitively-resolved v4).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

package.json

@@ -18,7 +18,8 @@
     "@anthropic-ai/claude-agent-sdk": "^0.3.212",
     "@koa/bodyparser": "^6.0.0",
     "@koa/router": "^14.0.0",
-    "koa": "^3.0.1"
+    "koa": "^3.0.1",
+    "zod": "^4.4.3"
   },
   "devDependencies": {
     "@types/koa": "^2.15.0",