feat(db): migrate from lowdb to SQLite with repos pattern

- Add modular DB layer (adapters, migrations, repos, helpers)
- Replace localDb/usageDb/requestDetailsDb monoliths with repos
- Add Tailscale tunnel integration & status check API
- Add /api/cli-tools/all-statuses aggregated endpoint
- Add settingsStore (Zustand) and mitm/dbReader
- Add DB unit tests (benchmark, concurrent, migration, vs-lowdb)

src/lib/db/index.js

@@ -0,0 +1,171 @@
+// Public API barrel — all DB functions
+import { getAdapter } from "./driver.js";
+import { stringifyJson, parseJson } from "./helpers/jsonCol.js";
+
+// Settings
+export {
+  getSettings, updateSettings, isCloudEnabled, getCloudUrl, exportSettings,
+} from "./repos/settingsRepo.js";
+
+// Provider connections
+export {
+  getProviderConnections, getProviderConnectionById,
+  createProviderConnection, updateProviderConnection,
+  deleteProviderConnection, deleteProviderConnectionsByProvider,
+  reorderProviderConnections, cleanupProviderConnections,
+} from "./repos/connectionsRepo.js";
+
+// Provider nodes
+export {
+  getProviderNodes, getProviderNodeById,
+  createProviderNode, updateProviderNode, deleteProviderNode,
+} from "./repos/nodesRepo.js";
+
+// Proxy pools
+export {
+  getProxyPools, getProxyPoolById,
+  createProxyPool, updateProxyPool, deleteProxyPool,
+} from "./repos/proxyPoolsRepo.js";
+
+// API keys
+export {
+  getApiKeys, getApiKeyById, createApiKey, updateApiKey, deleteApiKey, validateApiKey,
+} from "./repos/apiKeysRepo.js";
+
+// Combos
+export {
+  getCombos, getComboById, getComboByName,
+  createCombo, updateCombo, deleteCombo,
+} from "./repos/combosRepo.js";
+
+// Aliases (model + custom + mitm)
+export {
+  getModelAliases, setModelAlias, deleteModelAlias,
+  getCustomModels, addCustomModel, deleteCustomModel,
+  getMitmAlias, setMitmAliasAll,
+} from "./repos/aliasRepo.js";
+
+// Pricing
+export {
+  getPricing, getPricingForModel, updatePricing, resetPricing, resetAllPricing,
+} from "./repos/pricingRepo.js";
+
+// Disabled models
+export {
+  getDisabledModels, getDisabledByProvider, disableModels, enableModels,
+} from "./repos/disabledModelsRepo.js";
+
+// Usage
+export {
+  statsEmitter, trackPendingRequest, getActiveRequests,
+  saveRequestUsage, getUsageHistory, getUsageStats, getChartData,
+  appendRequestLog, getRecentLogs,
+} from "./repos/usageRepo.js";
+
+// Request details
+export {
+  saveRequestDetail, getRequestDetails, getRequestDetailById,
+} from "./repos/requestDetailsRepo.js";
+
+// Export/import full DB
+export async function exportDb() {
+  const db = await getAdapter();
+  const { exportSettings } = await import("./repos/settingsRepo.js");
+
+  const out = {
+    settings: await exportSettings(),
+    providerConnections: db.all(`SELECT * FROM providerConnections`).map((r) => ({ ...parseJson(r.data, {}), id: r.id, provider: r.provider, authType: r.authType, name: r.name, email: r.email, priority: r.priority, isActive: r.isActive === 1, createdAt: r.createdAt, updatedAt: r.updatedAt })),
+    providerNodes: db.all(`SELECT * FROM providerNodes`).map((r) => ({ ...parseJson(r.data, {}), id: r.id, type: r.type, name: r.name, createdAt: r.createdAt, updatedAt: r.updatedAt })),
+    proxyPools: db.all(`SELECT * FROM proxyPools`).map((r) => ({ ...parseJson(r.data, {}), id: r.id, isActive: r.isActive === 1, testStatus: r.testStatus, createdAt: r.createdAt, updatedAt: r.updatedAt })),
+    apiKeys: db.all(`SELECT * FROM apiKeys`).map((r) => ({ id: r.id, key: r.key, name: r.name, machineId: r.machineId, isActive: r.isActive === 1, createdAt: r.createdAt })),
+    combos: db.all(`SELECT * FROM combos`).map((r) => ({ id: r.id, name: r.name, kind: r.kind, models: parseJson(r.models, []), createdAt: r.createdAt, updatedAt: r.updatedAt })),
+    modelAliases: {},
+    customModels: [],
+    mitmAlias: {},
+    pricing: {},
+  };
+
+  for (const r of db.all(`SELECT key, value FROM kv WHERE scope = 'modelAliases'`)) out.modelAliases[r.key] = parseJson(r.value);
+  for (const r of db.all(`SELECT key, value FROM kv WHERE scope = 'customModels'`)) out.customModels.push(parseJson(r.value));
+  for (const r of db.all(`SELECT key, value FROM kv WHERE scope = 'mitmAlias'`)) out.mitmAlias[r.key] = parseJson(r.value);
+  for (const r of db.all(`SELECT key, value FROM kv WHERE scope = 'pricing'`)) out.pricing[r.key] = parseJson(r.value);
+
+  return out;
+}
+
+export async function importDb(payload) {
+  if (!payload || typeof payload !== "object" || Array.isArray(payload)) {
+    throw new Error("Invalid database payload");
+  }
+  const db = await getAdapter();
+
+  db.transaction(() => {
+    // Wipe all tables (keep _meta)
+    db.run(`DELETE FROM settings`);
+    db.run(`DELETE FROM providerConnections`);
+    db.run(`DELETE FROM providerNodes`);
+    db.run(`DELETE FROM proxyPools`);
+    db.run(`DELETE FROM apiKeys`);
+    db.run(`DELETE FROM combos`);
+    db.run(`DELETE FROM kv WHERE scope IN ('modelAliases', 'customModels', 'mitmAlias', 'pricing')`);
+
+    // Settings
+    if (payload.settings) {
+      db.run(`INSERT INTO settings(id, data) VALUES(1, ?) ON CONFLICT(id) DO UPDATE SET data = excluded.data`, [stringifyJson(payload.settings)]);
+    }
+
+    for (const c of payload.providerConnections || []) {
+      const { id, provider, authType, name, email, priority, isActive, createdAt, updatedAt, ...rest } = c;
+      db.run(
+        `INSERT OR REPLACE INTO providerConnections(id, provider, authType, name, email, priority, isActive, data, createdAt, updatedAt) VALUES(?, ?, ?, ?, ?, ?, ?, ?, ?, ?)`,
+        [id, provider, authType || "oauth", name || null, email || null, priority || null, isActive === false ? 0 : 1, stringifyJson(rest), createdAt || new Date().toISOString(), updatedAt || new Date().toISOString()]
+      );
+    }
+    for (const n of payload.providerNodes || []) {
+      const { id, type, name, createdAt, updatedAt, ...rest } = n;
+      db.run(
+        `INSERT OR REPLACE INTO providerNodes(id, type, name, data, createdAt, updatedAt) VALUES(?, ?, ?, ?, ?, ?)`,
+        [id, type || null, name || null, stringifyJson(rest), createdAt || new Date().toISOString(), updatedAt || new Date().toISOString()]
+      );
+    }
+    for (const p of payload.proxyPools || []) {
+      const { id, isActive, testStatus, createdAt, updatedAt, ...rest } = p;
+      db.run(
+        `INSERT OR REPLACE INTO proxyPools(id, isActive, testStatus, data, createdAt, updatedAt) VALUES(?, ?, ?, ?, ?, ?)`,
+        [id, isActive === false ? 0 : 1, testStatus || "unknown", stringifyJson(rest), createdAt || new Date().toISOString(), updatedAt || new Date().toISOString()]
+      );
+    }
+    for (const k of payload.apiKeys || []) {
+      db.run(
+        `INSERT OR REPLACE INTO apiKeys(id, key, name, machineId, isActive, createdAt) VALUES(?, ?, ?, ?, ?, ?)`,
+        [k.id, k.key, k.name || null, k.machineId || null, k.isActive === false ? 0 : 1, k.createdAt || new Date().toISOString()]
+      );
+    }
+    for (const c of payload.combos || []) {
+      db.run(
+        `INSERT OR REPLACE INTO combos(id, name, kind, models, createdAt, updatedAt) VALUES(?, ?, ?, ?, ?, ?)`,
+        [c.id, c.name, c.kind || null, stringifyJson(c.models || []), c.createdAt || new Date().toISOString(), c.updatedAt || new Date().toISOString()]
+      );
+    }
+    for (const [a, m] of Object.entries(payload.modelAliases || {})) {
+      db.run(`INSERT OR REPLACE INTO kv(scope, key, value) VALUES('modelAliases', ?, ?)`, [a, stringifyJson(m)]);
+    }
+    for (const m of payload.customModels || []) {
+      const k = `${m.providerAlias}|${m.id}|${m.type || "llm"}`;
+      db.run(`INSERT OR REPLACE INTO kv(scope, key, value) VALUES('customModels', ?, ?)`, [k, stringifyJson(m)]);
+    }
+    for (const [tool, mappings] of Object.entries(payload.mitmAlias || {})) {
+      db.run(`INSERT OR REPLACE INTO kv(scope, key, value) VALUES('mitmAlias', ?, ?)`, [tool, stringifyJson(mappings || {})]);
+    }
+    for (const [provider, models] of Object.entries(payload.pricing || {})) {
+      db.run(`INSERT OR REPLACE INTO kv(scope, key, value) VALUES('pricing', ?, ?)`, [provider, stringifyJson(models || {})]);
+    }
+  });
+
+  return await exportDb();
+}
+
+// Eager init helper (optional)
+export async function initDb() {
+  await getAdapter();
+}