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/i18n/package.json

@@ -14,7 +14,8 @@
     "lint": "oxlint",
     "format": "oxfmt --config ../../.oxfmtrc.json",
     "format:check": "oxfmt --check --config ../../.oxfmtrc.json",
-    "check-types": "tsc --noEmit"
+    "check-types": "tsc --noEmit",
+    "test": "vitest run"
   },
   "dependencies": {
     "@lingui/core": "catalog:",
@@ -24,8 +25,10 @@
     "@lingui/cli": "catalog:",
     "@lingui/conf": "catalog:",
     "@lingui/format-po": "catalog:",
+    "@sofa/tsconfig": "workspace:*",
     "@types/bun": "catalog:",
     "react": "catalog:",
-    "typescript": "catalog:"
+    "typescript": "catalog:",
+    "vitest": "catalog:"
   }
 }