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>

turbo.json

@@ -0,0 +1,22 @@
+{
+  "$schema": "https://turbo.build/schema.json",
+  "tasks": {
+    "build": {
+      "dependsOn": ["^build"],
+      "outputs": ["build/**", ".react-router/**"]
+    },
+    "dev": {
+      "cache": false,
+      "persistent": true
+    },
+    "lint": {
+      "dependsOn": ["^build"]
+    },
+    "test": {
+      "dependsOn": ["^build"]
+    },
+    "typecheck": {
+      "dependsOn": ["^build"]
+    }
+  }
+}