feat: add SPA, serve at /app/, update Dockerfile and README

- React + TanStack Router + shadcn/ui SPA under spa/
- serve spa/dist at /app/ with index.html fallback for client routing
- Dockerfile: node build stage for SPA, copy dist into runtime image
- README: document SPA, CORS_ORIGINS env var, architecture entry
- vite base set to /app/, manifest.json paths fixed

spa/src/lib/api/common.ts

@@ -0,0 +1,44 @@
+import { z } from "zod"
+
+export const movieDtoSchema = z.object({
+  id: z.string().uuid(),
+  title: z.string(),
+  release_year: z.number(),
+  director: z.string().optional(),
+  poster_path: z.string().optional(),
+  genres: z.array(z.string()),
+  runtime_minutes: z.number().optional(),
+  original_language: z.string().optional(),
+  overview: z.string().optional(),
+  collection_name: z.string().optional(),
+})
+export type MovieDto = z.infer<typeof movieDtoSchema>
+
+export const reviewDtoSchema = z.object({
+  id: z.string().uuid(),
+  rating: z.number(),
+  comment: z.string().optional(),
+  watched_at: z.string(),
+})
+export type ReviewDto = z.infer<typeof reviewDtoSchema>
+
+export const diaryEntryDtoSchema = z.object({
+  movie: movieDtoSchema,
+  review: reviewDtoSchema,
+})
+export type DiaryEntryDto = z.infer<typeof diaryEntryDtoSchema>
+
+export function paginatedSchema<T extends z.ZodType>(itemSchema: T) {
+  return z.object({
+    items: z.array(itemSchema),
+    total_count: z.number(),
+    limit: z.number(),
+    offset: z.number(),
+  })
+}
+export type Paginated<T> = {
+  items: T[]
+  total_count: number
+  limit: number
+  offset: number
+}