Add NextGen library: index DB, thumbnails, AI culling, and CLIP search

Builds the "indexed library" foundation and first intelligent features on
top of the organizer (sql.js index, non-destructive in-place indexing).

Phase 0 — Library index:
- sql.js (WASM SQLite) index DB; contentHash-keyed assets, resumable indexing
  (skip by path+mtime), batch persistence (chosen over native better-sqlite3
  which fails to build on Node 24 / Python 3.12)
- Library folders (in place, non-destructive) + background indexer w/ progress
- Thumbnails generated in the AI worker (canvas->webp), cached in userData;
  served via photoai-media://thumb by hash; thumbnail grid w/ pagination

Phase 1 — AI quality assessment & culling:
- Focus (Laplacian variance), exposure (histogram), eyes-open (face-api EAR)
  computed in one analyze pass alongside the thumbnail
- Culling filters (candidate/rejected) + quality badges
- Adjustable thresholds (live SQL re-classification from stored raw scores,
  no re-analysis) + manual star rating (0-5) and color labels (usermeta)

Phase 2 — CLIP natural-language / similarity search:
- @huggingface/transformers (WASM/WebGPU, no native build)
- CLIP image/text embeddings (lazy-loaded); Korean queries auto-translated
  via opus-mt-ko-en into the English CLIP
- Embeddings stored as SQLite BLOBs; "build search index" batch w/ progress;
  brute-force cosine search; new Search tab
- Note: models download from HF Hub on first use; fully-offline ORT-wasm
  packaging and KO search-accuracy tuning are follow-ups

Tabs added (Organize / Library / Search). All typecheck/tests(12)/build green;
boot smoke verified across phases.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/shared/constants.ts

@@ -50,6 +50,22 @@ export const DEFAULT_JOB_OPTIONS = {
 /** 추론 시 이미지 장변 최대 픽셀 (다운스케일 기준) */
 export const MAX_IMAGE_DIMENSION = 1024
 
+/** 썸네일 장변 픽셀 */
+export const THUMBNAIL_SIZE = 256
+
+/** 품질 분석 시 이미지 장변 픽셀 (초점/노출/얼굴 계산용) */
+export const ANALYZE_SIZE = 512
+
+/** 품질 판정 기본 임계값 (Phase 1) */
+export const QUALITY_THRESHOLDS = {
+  /** 라플라시안 분산이 이 값 미만이면 흐림 (512px 기준) */
+  focus: 60,
+  /** 노출 점수(0~1)가 이 값 미만이면 노출 불량 */
+  exposure: 0.35,
+  /** EAR(눈 종횡비)이 이 값 미만이면 눈 감음 */
+  eyes: 0.18
+}
+
 /** IPC 채널명 */
 export const IPC = {
   // UI → Main (invoke)
@@ -73,6 +89,24 @@ export const IPC = {
   SETTINGS_GET: 'settings:get',
   SETTINGS_SET: 'settings:set',
   SETTINGS_CHANGED: 'settings:changed',
+  // 라이브러리 / 색인 (Phase 0)
+  LIBRARY_LIST: 'library:list',
+  LIBRARY_ADD: 'library:add',
+  LIBRARY_REMOVE: 'library:remove',
+  INDEX_RUN: 'index:run',
+  INDEX_CANCEL: 'index:cancel',
+  INDEX_PROGRESS: 'index:progress',
+  INDEX_DONE: 'index:done',
+  INDEX_ASSETS: 'index:assets',
+  INDEX_SET_RATING: 'index:setRating',
+  INDEX_SET_LABEL: 'index:setLabel',
+  // 검색 (Phase 2)
+  SEARCH_BUILD: 'search:build',
+  SEARCH_CANCEL: 'search:cancel',
+  SEARCH_STATUS: 'search:status',
+  SEARCH_QUERY: 'search:query',
+  SEARCH_PROGRESS: 'search:progress',
+  SEARCH_DONE: 'search:done',
   // Main → UI (send)
   JOB_PROGRESS: 'job:progress',
   JOB_FILE_PROCESSED: 'job:fileProcessed',