feat: add SQLite schema for PDS storage

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <[e-mail]>

src/pds.js

···
   constructor(state, env) {
     this.state = state
     this.sql = state.storage.sql
+    this.env = env
+
+    // Initialize schema
+    this.sql.exec(`
+      CREATE TABLE IF NOT EXISTS blocks (
+        cid TEXT PRIMARY KEY,
+        data BLOB NOT NULL
+      );
+
+      CREATE TABLE IF NOT EXISTS records (
+        uri TEXT PRIMARY KEY,
+        cid TEXT NOT NULL,
+        collection TEXT NOT NULL,
+        rkey TEXT NOT NULL,
+        value BLOB NOT NULL
+      );
+
+      CREATE TABLE IF NOT EXISTS commits (
+        seq INTEGER PRIMARY KEY AUTOINCREMENT,
+        cid TEXT NOT NULL,
+        rev TEXT NOT NULL,
+        prev TEXT
+      );
+
+      CREATE TABLE IF NOT EXISTS seq_events (
+        seq INTEGER PRIMARY KEY AUTOINCREMENT,
+        did TEXT NOT NULL,
+        commit_cid TEXT NOT NULL,
+        evt BLOB NOT NULL
+      );
+
+      CREATE INDEX IF NOT EXISTS idx_records_collection ON records(collection, rkey);
+    `)
   }
 
   async fetch(request) {
···
     if (url.pathname === '/test/tid') {
       const tids = [createTid(), createTid(), createTid()]
       return Response.json({ tids })
+    }
+    if (url.pathname === '/test/schema') {
+      const tables = this.sql.exec(`
+        SELECT name FROM sqlite_master WHERE type='table' ORDER BY name
+      `).toArray()
+      return Response.json({ tables: tables.map(t => t.name) })
     }
     return new Response('pds running', { status: 200 })
   }