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/disabledModelsDb.js

@@ -1,67 +1,4 @@
-import { Low } from "lowdb";
-import { JSONFile } from "lowdb/node";
-import path from "node:path";
-import fs from "node:fs";
-import { DATA_DIR } from "@/lib/dataDir.js";
-
-const DB_FILE = path.join(DATA_DIR, "disabledModels.json");
-
-if (!fs.existsSync(DATA_DIR)) fs.mkdirSync(DATA_DIR, { recursive: true });
-
-const defaultData = { disabled: {} };
-
-let dbInstance = null;
-
-async function getDb() {
-  if (!dbInstance) {
-    const adapter = new JSONFile(DB_FILE);
-    dbInstance = new Low(adapter, defaultData);
-    try {
-      await dbInstance.read();
-    } catch (error) {
-      if (error instanceof SyntaxError) {
-        dbInstance.data = { ...defaultData };
-        await dbInstance.write();
-      } else {
-        throw error;
-      }
-    }
-    if (!dbInstance.data || typeof dbInstance.data !== "object") dbInstance.data = { ...defaultData };
-    if (!dbInstance.data.disabled) dbInstance.data.disabled = {};
-  }
-  return dbInstance;
-}
-
-export async function getDisabledModels() {
-  const db = await getDb();
-  return db.data.disabled || {};
-}
-
-export async function getDisabledByProvider(providerAlias) {
-  const all = await getDisabledModels();
-  return all[providerAlias] || [];
-}
-
-export async function disableModels(providerAlias, ids) {
-  if (!providerAlias || !Array.isArray(ids)) return;
-  const db = await getDb();
-  const current = new Set(db.data.disabled[providerAlias] || []);
-  ids.forEach((id) => current.add(id));
-  db.data.disabled[providerAlias] = [...current];
-  await db.write();
-}
-
-export async function enableModels(providerAlias, ids) {
-  if (!providerAlias) return;
-  const db = await getDb();
-  const current = db.data.disabled[providerAlias] || [];
-  if (!Array.isArray(ids) || ids.length === 0) {
-    delete db.data.disabled[providerAlias];
-  } else {
-    const removeSet = new Set(ids);
-    const next = current.filter((id) => !removeSet.has(id));
-    if (next.length === 0) delete db.data.disabled[providerAlias];
-    else db.data.disabled[providerAlias] = next;
-  }
-  await db.write();
-}
+// Shim → re-export from new SQLite-based DB layer (src/lib/db/)
+export {
+  getDisabledModels, getDisabledByProvider, disableModels, enableModels,
+} from "@/lib/db/index.js";