Implement async Database API (breaking change) #6

Breaking Change: Async Database API

Convert all Database methods from sync to async for browser compatibility.

Rationale

• Browser WASM requires async (no sync file I/O)
• Universal API works everywhere
• No breaking changes concern (pre-v1.0, zero adoption)

Scope

• Database.create() - Factory method
• createNode(), createEdge() - CRUD ops
• nodes(), edges() - Query builders
• transaction() - Transaction handling
• All NodeQuery methods
• All TraversalQuery methods
• Update all tests (234+ tests)
• Update all examples
• Update all documentation

Migration Example

// Before (v0.x - sync)
const db = new GraphDatabase('./graph.db');
const node = db.createNode('Job', { title: 'Engineer' });

// After (v1.0 - async)
const db = await GraphDatabase.create('./graph.db');
const node = await db.createNode('Job', { title: 'Engineer' });

AgentDB Info

Pattern: async-api-migration
Complexity: High (4-6 hours estimated)
Recommended Approach: SPARC multi-agent swarm
Agents Needed: specification, architect, coder (2x parallel), tester, reviewer

References

• Adapter pattern: experiments/browser-poc/
• NodeAdapter: sync wrapper for better-sqlite3
• BrowserAdapter: native async for wa-sqlite