feat(01-01): wire Clerk proxy.ts, Prisma 7 schema + singleton, tRPC stack, R2 client, ActivePetContext

- Create proxy.ts at repo root with clerkMiddleware + createRouteMatcher (public allowlist: sign-up, log-in, forgot-password, reset-password, verify-email)
- Create prisma/schema.prisma: Owner, Species, Breed, Pet models with ownership index and FK constraints
- Create prisma.config.ts with Prisma 7 defineConfig (datasource url via env)
- Create src/lib/prisma.ts: Prisma 7 singleton using @prisma/adapter-pg for local dev, withAccelerate() for Prisma Accelerate on Vercel
- Create src/lib/r2.ts (server-only): S3Client + getPresignedUploadUrl with contentType enforcement and 300s expiry
- Create src/lib/auth.ts: getOwnerId() Clerk auth wrapper
- Create src/trpc/init.ts: createTRPCContext, router, publicProcedure, protectedProcedure (throws UNAUTHORIZED)
- Create src/trpc/routers/pets.ts: pets.create (upserts Owner, creates Pet with ownerId=ctx.userId), pets.list (scoped), pets.byId (ownership-asserted)
- Create src/trpc/routers/_app.ts: appRouter + AppRouter type export
- Create src/trpc/query-client.ts, server.ts (RSC caller), client.tsx (TRPCReactProvider + useTRPC)
- Create src/app/api/trpc/[trpc]/route.ts: tRPC fetch handler (GET + POST)
- Create src/context/ActivePetContext.tsx + src/hooks/useActivePet.ts: localStorage-backed active pet context
- Create prisma/seed.ts: seeds Dog/Cat/Bird species idempotently via upsert
- Update src/app/layout.tsx: wrap children in ClerkProvider (orange primary), TRPCReactProvider, ActivePetProvider, Toaster
- Install @prisma/adapter-pg + pg for Prisma 7 local dev (Rule 2: required for Prisma 7 engine compatibility)
- [Rule 1 - Bug] Prisma 7 no longer supports url/directUrl in schema.prisma; moved to prisma.config.ts with defineConfig

src/app/api/trpc/[trpc]/route.ts

@@ -0,0 +1,17 @@
+import { fetchRequestHandler } from "@trpc/server/adapters/fetch";
+import { appRouter } from "@/trpc/routers/_app";
+import { createTRPCContext } from "@/trpc/init";
+
+/**
+ * tRPC fetch handler for Next.js App Router.
+ * Handles all tRPC requests via the /api/trpc endpoint.
+ */
+const handler = (req: Request) =>
+  fetchRequestHandler({
+    endpoint: "/api/trpc",
+    req,
+    router: appRouter,
+    createContext: createTRPCContext,
+  });
+
+export { handler as GET, handler as POST };