Initial monorepo setup with architecture plan

- Monorepo structure: apps/ (planner, journal) + packages/ (ui, types, map, gpx, i18n)
- Tooling: pnpm workspaces + Turborepo
- Architecture plan documenting all resolved decisions from design review
- Shared types package with Route, Activity, and Waypoint interfaces
- MIT license

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/types/src/index.ts

@@ -0,0 +1,57 @@
+/**
+ * Shared TypeScript types for trails.cool
+ *
+ * These types are used by both the Planner and Journal apps.
+ */
+
+export interface Waypoint {
+  lat: number;
+  lon: number;
+  name?: string;
+  isDayBreak?: boolean;
+}
+
+export interface RouteMetadata {
+  created: Date;
+  updated: Date;
+  owner: string;
+  contributors: string[];
+  routingProfile: string;
+  dayBreaks: number[];
+  distance: number;
+  elevation: {
+    gain: number;
+    loss: number;
+  };
+  tags: string[];
+}
+
+export interface Route {
+  id: string;
+  name: string;
+  description: string;
+  gpx: string;
+  metadata: RouteMetadata;
+  plannerState?: Uint8Array;
+  versions: RouteVersion[];
+}
+
+export interface RouteVersion {
+  version: number;
+  gpx: string;
+  createdAt: Date;
+  createdBy: string;
+  changeDescription?: string;
+}
+
+export interface Activity {
+  id: string;
+  routeId?: string;
+  name: string;
+  description: string;
+  gpx: string;
+  startedAt: Date;
+  duration: number;
+  photos: string[];
+  participants: string[];
+}