chore: migrate to v3, Doppler secrets, clean up legacy code

- Remove all pre-v3 code: scraper, ui-v2, backend v1, ios v1+v2, legacy CI workflows
- Flatten v3/ contents to repo root
- Add Doppler secrets management (project=libnovel, config=prd)
- Add justfile with doppler run wrappers for all docker compose commands
- Strip hardcoded env fallbacks from docker-compose.yml
- Add minimal README.md
- Clean up .gitignore

backend/internal/orchestrator/orchestrator.go

@@ -5,6 +5,8 @@
 //   - RunBook scrapes one book (metadata + chapter list + chapter texts) end-to-end.
 //   - N worker goroutines pull chapter refs from a shared queue and call ScrapeChapterText.
 //   - The caller (runner poll loop) owns the outer task-claim / finish cycle.
+//   - An optional PostMetadata hook (set in Config) is called after WriteMetadata
+//     succeeds. The runner uses this to upsert books into Meilisearch.
 package orchestrator
 
 import (
@@ -25,14 +27,19 @@ type Config struct {
 	// Workers is the number of goroutines used to scrape chapters in parallel.
 	// Defaults to runtime.NumCPU() when 0.
 	Workers int
+	// PostMetadata is an optional hook called with the scraped BookMeta after
+	// WriteMetadata succeeds. Errors from the hook are logged but not fatal.
+	// Used by the runner to index books in Meilisearch.
+	PostMetadata func(ctx context.Context, meta domain.BookMeta)
 }
 
 // Orchestrator runs a single-book scrape pipeline.
 type Orchestrator struct {
-	novel   scraper.NovelScraper
-	store   bookstore.BookWriter
-	log     *slog.Logger
-	workers int
+	novel        scraper.NovelScraper
+	store        bookstore.BookWriter
+	log          *slog.Logger
+	workers      int
+	postMetadata func(ctx context.Context, meta domain.BookMeta)
 }
 
 // New returns a new Orchestrator.
@@ -44,7 +51,13 @@ func New(cfg Config, novel scraper.NovelScraper, store bookstore.BookWriter, log
 	if workers <= 0 {
 		workers = runtime.NumCPU()
 	}
-	return &Orchestrator{novel: novel, store: store, log: log, workers: workers}
+	return &Orchestrator{
+		novel:        novel,
+		store:        store,
+		log:          log,
+		workers:      workers,
+		postMetadata: cfg.PostMetadata,
+	}
 }
 
 // RunBook scrapes a single book described by task. It handles:
@@ -84,12 +97,16 @@ func (o *Orchestrator) RunBook(ctx context.Context, task domain.ScrapeTask) doma
 		result.Errors++
 	} else {
 		result.BooksFound = 1
+		// Fire optional post-metadata hook (e.g. Meilisearch indexing).
+		if o.postMetadata != nil {
+			o.postMetadata(ctx, meta)
+		}
 	}
 
 	o.log.Info("metadata saved", "slug", meta.Slug, "title", meta.Title)
 
 	// ── Step 2: Chapter list ──────────────────────────────────────────────────
-	refs, err := o.novel.ScrapeChapterList(ctx, task.TargetURL)
+	refs, err := o.novel.ScrapeChapterList(ctx, task.TargetURL, task.ToChapter)
 	if err != nil {
 		o.log.Error("chapter list scrape failed", "slug", meta.Slug, "err", err)
 		result.ErrorMessage = fmt.Sprintf("chapter list: %v", err)

backend/internal/orchestrator/orchestrator_test.go

@@ -34,7 +34,7 @@ func (s *stubScraper) ScrapeMetadata(_ context.Context, _ string) (domain.BookMe
 	return s.meta, s.metaErr
 }
 
-func (s *stubScraper) ScrapeChapterList(_ context.Context, _ string) ([]domain.ChapterRef, error) {
+func (s *stubScraper) ScrapeChapterList(_ context.Context, _ string, _ int) ([]domain.ChapterRef, error) {
 	return s.refs, s.refsErr
 }