chore: extract shared tsconfig, move display-status to core, add i18n tests

- Add `@sofa/tsconfig` package with a shared `base.json` (target, lib, strict, moduleResolution, etc.) and migrate all packages/apps to `"extends": "@sofa/tsconfig/base.json"` to eliminate duplicated compiler options
- Move `display-status.ts` (and its `DisplayStatus` type + `getDisplayStatus` fn) from `@sofa/api` to `@sofa/core`; remove the `./display-status` export from `@sofa/api` and update all import sites in `discovery.ts` and `tracking.ts`
- Add `packages/core/test/display-status.test.ts`: 15 tests covering `ONGOING_TMDB_STATUSES` and all `getDisplayStatus` branches (movie, TV watchlist/in_progress/caught_up/completed, edge cases)
- Add `packages/i18n/vitest.config.ts` and two new test files: `date-buckets.test.ts` and `format.test.ts` covering date bucketing and locale formatting utilities

packages/core/src/discovery.ts

@@ -1,4 +1,3 @@
-import type { DisplayStatus } from "@sofa/api/display-status";
 import {
   getAllTrackedTitleIds,
   getAvailabilityByTitleIds,
@@ -25,6 +24,7 @@ import {
 } from "@sofa/db/queries/discovery";
 import { tmdbImageUrl } from "@sofa/tmdb/image";
 
+import type { DisplayStatus } from "./display-status";
 import { getDisplayStatusesByTitleIds } from "./tracking";
 
 function formatLocalDate(d: Date): string {

packages/core/src/display-status.ts

@@ -0,0 +1,32 @@
+export type StoredStatus = "watchlist" | "in_progress" | "completed";
+
+export type DisplayStatus = "in_watchlist" | "watching" | "caught_up" | "completed";
+
+export const ONGOING_TMDB_STATUSES = ["Returning Series", "In Production"];
+
+/**
+ * Derive the user-facing display status from stored status + context.
+ *
+ * Movies: watchlist → in_watchlist, completed → completed
+ * TV:     watchlist → in_watchlist, in_progress → watching | caught_up | completed
+ */
+export function getDisplayStatus(
+  storedStatus: StoredStatus,
+  titleType: "movie" | "tv",
+  tmdbStatus: string | null,
+  episodeProgress: { watched: number; total: number } | null,
+): DisplayStatus {
+  if (storedStatus === "watchlist") return "in_watchlist";
+  if (titleType === "movie") return storedStatus === "completed" ? "completed" : "in_watchlist";
+
+  // TV with in_progress: derive from episode progress + TMDB show status
+  if (
+    episodeProgress &&
+    episodeProgress.total > 0 &&
+    episodeProgress.watched >= episodeProgress.total
+  ) {
+    return ONGOING_TMDB_STATUSES.includes(tmdbStatus ?? "") ? "caught_up" : "completed";
+  }
+
+  return "watching";
+}

packages/core/src/tracking.ts

@@ -1,5 +1,3 @@
-import type { DisplayStatus } from "@sofa/api/display-status";
-import { getDisplayStatus } from "@sofa/api/display-status";
 import { getTitlesByIds } from "@sofa/db/queries/discovery";
 import { getTitleById } from "@sofa/db/queries/title";
 import {
@@ -25,6 +23,9 @@ import {
   upsertTitleStatus,
 } from "@sofa/db/queries/tracking";
 
+import type { DisplayStatus } from "./display-status";
+import { getDisplayStatus } from "./display-status";
+
 export function setTitleStatus(
   userId: string,
   titleId: string,