feat(trips): trip tracking with analytics, tag conversion, and transaction assignment

Adds trips table usage across API and UI: trip CRUD, per-trip analytics
(category/daily/merchant/tag/participant breakdowns), tag-to-trip
conversion, trip assignment via transaction overrides, and trip filter
in the transactions view. Recovered from working tree after local git
corruption; feature was already live via host-context Docker builds.

src/components/sidebar.tsx

@@ -7,6 +7,7 @@ import { useState, useEffect } from "react";
 const NAV_ITEMS = [
   { href: "/transactions", label: "Transactions", icon: "receipt" },
   { href: "/statements", label: "Statements", icon: "file-text" },
+  { href: "/trips", label: "Trips", icon: "map-pin" },
   { href: "/shared", label: "Shared", icon: "users" },
   { href: "/budget", label: "Analytics", icon: "bar-chart" },
   { href: "/insights", label: "Insights", icon: "lightbulb" },
@@ -27,6 +28,12 @@ const ICONS: Record<string, React.ReactNode> = {
       <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M9 12h6m-6 4h6m2 5H7a2 2 0 01-2-2V5a2 2 0 012-2h5.586a1 1 0 01.707.293l5.414 5.414a1 1 0 01.293.707V19a2 2 0 01-2 2z" />
     </svg>
   ),
+  "map-pin": (
+    <svg className="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+      <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M17.657 16.657L13.414 20.9a1.998 1.998 0 01-2.827 0l-4.244-4.243a8 8 0 1111.314 0z" />
+      <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M15 11a3 3 0 11-6 0 3 3 0 016 0z" />
+    </svg>
+  ),
   users: (
     <svg className="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
       <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M12 4.354a4 4 0 110 5.292M15 21H3v-1a6 6 0 0112 0v1zm0 0h6v-1a6 6 0 00-9-5.197M13 7a4 4 0 11-8 0 4 4 0 018 0z" />