feat(mcpedia): Phase 2 — semantic + hybrid search, tRPC/Hono API

- @mcpedia/embeddings: OpenRouter provider (9router /v1, encoding_format float),
  chunkText + embedChunks; EMBED_DIM=2048
- document_chunks table (real[] embedding) — pgvector NOT available on shared
  imrnes Postgres, so cosine is computed in-app (KB-scale fine); pgvector deferred
- indexer: chunk + embed + upsert per document
- @mcpedia/search: semanticSearch (cosine) + hybridSearch (FTS+cosine RRF)
- apps/api: Hono + tRPC v11 (6 procedures), serve on :4020
- MCP: semantic_search + hybrid_search tools (6 total)
- web: keyword/hybrid toggle; .env.example + README + PHASES updated

packages/embeddings/package.json

@@ -0,0 +1,17 @@
+{
+  "name": "@mcpedia/embeddings",
+  "version": "0.1.0",
+  "private": true,
+  "type": "module",
+  "main": "./src/index.ts",
+  "exports": {
+    ".": "./src/index.ts"
+  },
+  "dependencies": {
+    "@mcpedia/config": "workspace:*",
+    "@mcpedia/types": "workspace:*"
+  },
+  "devDependencies": {
+    "typescript": "^5.6.0"
+  }
+}