Phase 7: MIT license, portfolio README, Docker, cross-platform start

- LICENSE: MIT
- README: rewritten as portfolio-grade docs (features with code pointers,
  architecture, Docker/Windows/macOS quick starts, BYO-model table)
- Dockerfile (3-stage: SPA build, pip wheels, slim runtime) + compose with
  a /data volume; .dockerignore keeps secrets and local data out
- database.py: AIDND_DB_PATH env override so deployments can relocate the
  SQLite file; documented in backend/.env.example
- start.sh: macOS/Linux dev script with first-run setup

Verified locally: production SPA build served by the backend (deep links
OK), DB created at the override path. Docker image itself untested here
(Docker not installed); flagged in plan/07.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KFsGHju9szibJJa2YJcdbg

start.sh

@@ -0,0 +1,23 @@
+#!/usr/bin/env bash
+# macOS/Linux equivalent of start.ps1: backend (FastAPI, :8000) and frontend
+# dev server (Vite, :5173). Ctrl-C stops both.
+set -euo pipefail
+cd "$(dirname "$0")"
+
+if [ ! -d backend/.venv ]; then
+  echo "First-time setup: creating backend/.venv and installing dependencies..."
+  python3 -m venv backend/.venv
+  backend/.venv/bin/pip install -r backend/requirements.txt
+fi
+if [ ! -d frontend/node_modules ]; then
+  echo "First-time setup: npm install..."
+  (cd frontend && npm install)
+fi
+
+(cd backend && .venv/bin/uvicorn app.main:app --port 8000 --reload) &
+BACKEND_PID=$!
+trap 'kill "$BACKEND_PID" 2>/dev/null' EXIT
+
+echo "Backend:  http://localhost:8000  (API docs: http://localhost:8000/docs)"
+echo "Frontend: http://localhost:5173"
+cd frontend && npm run dev