feat: add Kokoro TTS, ranking page, direct HTTP strategy, and chapter-number fix

- Add Kokoro-FastAPI TTS integration to the chapter reader UI:
  - Browser-side MSE streaming with paragraph-level click-to-start
  - Voice selector, speed slider, auto-next with prefetch of the next chapter
  - New GET /ui/chapter-text endpoint that strips Markdown and serves plain text

- Add ranking page (novelfire /ranking scraper, WriteRanking/ReadRankingItems
  in writer, GET /ranking + POST /ranking/refresh + GET /ranking/view routes)
  with local-library annotation and one-click scrape buttons

- Add StrategyDirect (plain HTTP client) as a new browser strategy; the
  default strategy is now 'direct' for chapter fetching and 'content'
  for chapter-list URL retrieval (split via BROWSERLESS_URL_STRATEGY)

- Fix chapter numbering bug: numbers are now derived from the URL path
  (/chapter-N) rather than list position, correcting newest-first ordering

- Add 'refresh <slug>' CLI sub-command to re-scrape a book from its saved
  source_url without knowing the original URL

- Extend NovelScraper interface with RankingProvider (ScrapeRanking)

- Tune scraper timeouts: wait-for-selector reduced to 5 s, GotoOptions
  timeout set to 60 s, content/scrape client defaults raised to 90 s

- Add cover extraction fix (figure.cover > img rather than bare img.cover)

- Add AGENTS.md and .aiignore for AI tooling context

- Add integration tests for browser client and novelfire scraper (build
  tag: integration) and unit tests for chapterNumberFromURL and pagination

scraper/internal/scraper/interfaces.go

@@ -27,6 +27,8 @@ type BookMeta struct {
 	TotalChapters int `yaml:"total_chapters,omitempty"`
 	// SourceURL is the canonical URL of the book's landing page.
 	SourceURL string `yaml:"source_url"`
+	// Ranking is the rank number from ranking pages.
+	Ranking int `yaml:"ranking,omitempty"`
 }
 
 // CatalogueEntry is a lightweight reference returned by CatalogueProvider.
@@ -108,6 +110,13 @@ type ChapterTextProvider interface {
 	ScrapeChapterText(ctx context.Context, ref ChapterRef) (Chapter, error)
 }
 
+// RankingProvider can enumerate novels from a ranking page.
+type RankingProvider interface {
+	// ScrapeRanking pages through the ranking list, sending BookMeta values
+	// (with basic info like title, cover, genres, status, sourceURL) to the returned channel.
+	ScrapeRanking(ctx context.Context) (<-chan BookMeta, <-chan error)
+}
+
 // NovelScraper is the full interface that a concrete novel source must implement.
 // It composes all four provider interfaces.
 type NovelScraper interface {
@@ -115,6 +124,7 @@ type NovelScraper interface {
 	MetadataProvider
 	ChapterListProvider
 	ChapterTextProvider
+	RankingProvider
 
 	// SourceName returns the human-readable name of this scraper, e.g. "novelfire.net".
 	SourceName() string