one source of truth for Route/Activity shapes; enforce api contracts

Route and Activity existed three times: hand-written interfaces in
packages/types, Zod contracts in packages/api, and Drizzle columns in
packages/db — each with different fields and nullability. The
hand-written ones had drifted so far they had zero importers; the Zod
contracts were advisory because v1 handlers hand-rolled Response.json
shapes nothing validated.

- packages/types keeps only what both apps actually share (Waypoint,
  WaypointPoiTags) and documents where row types and wire contracts
  live; the dead Route/RouteMetadata/RouteVersion/Activity interfaces
  are gone
- packages/db exports canonical inferred row types (RouteRow,
  ActivityRow, RouteVersionRow, UserRow)
- packages/api contracts are reconciled with the real wire format
  (RouteVersionSchema gains the id and createdBy fields the endpoint
  has always returned) and gain Create*ResponseSchemas
- apiJson(schema, payload) in api-guard parses every v1 response
  through its contract: drift is now a thrown ZodError in tests/CI,
  unknown keys are stripped, and payloads are compile-checked as
  z.input of the schema

Enforcement immediately caught two real drifts: nullable DB
descriptions could ship null where the contract promises string (now
coalesced at the boundary), and GET /api/v1/activities/:id was missing
the routeName and photos fields its contract declares.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

packages/types/src/index.ts

@@ -1,7 +1,13 @@
 /**
- * Shared TypeScript types for trails.cool
+ * Shared TypeScript types for trails.cool — the Waypoint wire format
+ * used by both the Planner and Journal apps (Yjs document, GPX
+ * extensions, handoff payloads).
  *
- * These types are used by both the Planner and Journal apps.
+ * Not here on purpose: database row types are derived from the Drizzle
+ * schema (@trails-cool/db, e.g. RouteRow), and API response shapes are
+ * the Zod contracts in @trails-cool/api. Earlier hand-written Route /
+ * Activity interfaces in this file drifted from both and had zero
+ * importers when they were removed.
  */
 
 export interface WaypointPoiTags {
@@ -26,48 +32,3 @@ export interface Waypoint {
   osmId?: number;
   poiTags?: WaypointPoiTags;
 }
-
-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[];
-}