Phase 1: Go backend scaffold

- Project structure: cmd/boosapi, internal/, pkg/
- Config loader (all env vars from Node.js original)
- Database layer with SQLite/MySQL/Postgres support
- Migration runner (sequential SQL files)
- Health check endpoint (GET /healthz)
- HTTP middleware: logger, auth, CORS, panic recovery
- chi router with /admin, /v1, /api route groups
- Graceful shutdown (SIGINT/SIGTERM)
- Multi-stage Dockerfile (alpine, ~20MB image)
- Initial schema migration (users, api_keys, sites, usage_logs)

Signed-off-by: Boos4721 <boos4721@icloud.com>

internal/db/migrate/000001_initial.up.sql

@@ -0,0 +1,50 @@
+-- Initial schema
+-- Compatible with SQLite, MySQL, and PostgreSQL
+
+CREATE TABLE IF NOT EXISTS users (
+    id          TEXT PRIMARY KEY,
+    username    TEXT NOT NULL UNIQUE,
+    email       TEXT,
+    role        TEXT NOT NULL DEFAULT 'user',
+    created_at  TEXT NOT NULL DEFAULT (datetime('now')),
+    updated_at  TEXT NOT NULL DEFAULT (datetime('now'))
+);
+
+CREATE TABLE IF NOT EXISTS api_keys (
+    id          TEXT PRIMARY KEY,
+    user_id     TEXT NOT NULL REFERENCES users(id),
+    key_hash    TEXT NOT NULL,
+    name        TEXT NOT NULL DEFAULT '',
+    enabled     INTEGER NOT NULL DEFAULT 1,
+    created_at  TEXT NOT NULL DEFAULT (datetime('now')),
+    expires_at  TEXT
+);
+
+CREATE TABLE IF NOT EXISTS sites (
+    id          TEXT PRIMARY KEY,
+    name        TEXT NOT NULL,
+    type        TEXT NOT NULL DEFAULT 'openai',
+    base_url    TEXT NOT NULL,
+    api_key     TEXT NOT NULL DEFAULT '',
+    priority    INTEGER NOT NULL DEFAULT 0,
+    weight      REAL NOT NULL DEFAULT 1.0,
+    enabled     INTEGER NOT NULL DEFAULT 1,
+    created_at  TEXT NOT NULL DEFAULT (datetime('now')),
+    updated_at  TEXT NOT NULL DEFAULT (datetime('now'))
+);
+
+CREATE TABLE IF NOT EXISTS usage_logs (
+    id              TEXT PRIMARY KEY,
+    user_id         TEXT REFERENCES users(id),
+    site_id         TEXT REFERENCES sites(id),
+    model           TEXT NOT NULL,
+    prompt_tokens   INTEGER NOT NULL DEFAULT 0,
+    completion_tokens INTEGER NOT NULL DEFAULT 0,
+    total_tokens    INTEGER NOT NULL DEFAULT 0,
+    cost            REAL NOT NULL DEFAULT 0,
+    request_at      TEXT NOT NULL DEFAULT (datetime('now'))
+);
+
+CREATE INDEX IF NOT EXISTS idx_usage_logs_user_id ON usage_logs(user_id);
+CREATE INDEX IF NOT EXISTS idx_usage_logs_request_at ON usage_logs(request_at);
+CREATE INDEX IF NOT EXISTS idx_api_keys_user_id ON api_keys(user_id);