feat(architecture): Implement clean 3-layer architecture with ports & adapters

Major refactoring to separate concerns into three distinct layers:

## Core Layer (Pure Business Logic)
- Created @starfleet/data-core package with zero Node.js dependencies
- Implemented ports as pure TypeScript-style JSDoc interfaces
- Added application use-cases: GenerateMigrationPlan, ApplyMigrationPlan, VerifySafetyGates
- Defined domain types and event constants
- No I/O, no console, no process - pure functions only

## Host-Node Layer (Adapters)
- Created @starfleet/data-host-node package with Node.js implementations
- Implemented all port adapters: FileSystem, Glob, Clock, Environment, Logger, EventBus, Git, Db, Process, Crypto
- Single-connection transaction support in DbPortNodeAdapter
- Cross-platform ProcessPort.which() for Windows/Unix compatibility
- EventBus returns unsubscribe functions for clean resource management

## CLI Layer (Presentation)
- Created @starfleet/data-cli package as thin presentation layer
- Composition root in buildServices.js wires all dependencies
- Runtime port validation with ensurePort()
- Extracted reporter to separate module for clean separation
- Commands are now thin orchestrators calling use-cases

## Architecture Improvements
- ESLint rules enforce layer boundaries (no Node in core!)
- Package exports use /* patterns for proper directory mapping
- Workspace configuration for npm monorepo
- Smoke test for verifying DI container wiring
- All adapters validated at startup for fail-fast behavior

This architecture enables:
- Unit testing core logic without I/O
- Swappable implementations via ports
- Future API/GUI without touching business logic
- Clean dependency flow: CLI → Host-Node → Core

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

Co-Authored-By: Claude <[email protected]>

Author: flyingrobots

CLAUDE.md

@@ -208,4 +208,5 @@ For TypeScript projects, use `@typescript-eslint/no-floating-promises` to catch
 ### Recent Fixes
 - Fixed error handling in CompileCommand constructor to properly display errors
 - Added `isProd` property to start event emissions
-- Fixed MigrationCompiler config property naming (sqlDir vs rootDir)
+- Fixed MigrationCompiler config property naming (sqlDir vs rootDir)
+- CRITICAL: ABSOLUTELY ZERO TYPESCRIPT ALLOWED, CLAUDE. Very slim exceptions to this rule (Edge Function generation nonsense). For information, see @import @docs/decisions/000-javascript-not-typescript.md