feat(browse): add SingleFile browse-page snapshot cache via MinIO

- New MinIO bucket 'libnovel-browse' (MINIO_BUCKET_BROWSE env) for storing
  self-contained HTML snapshots of novelfire browse pages
- Store interface gains SaveBrowsePage / GetBrowsePage / BrowsePageKey methods
- handleBrowse is now cache-first: serves from MinIO snapshot when available,
  then fires a background triggerBrowseSnapshot goroutine to populate cache
  on live-fetch (de-duplicated, 90s timeout)
- New 'save-browse' CLI subcommand to bulk-capture pages via SingleFile CLI
- Dockerfile: downloads pinned single-file-x86_64-linux binary (v2.0.83),
  adds gcompat + libstdc++ to Alpine runtime for glibc compatibility
- docker-compose: adds libnovel-browse bucket init and SINGLEFILE_PATH env
- .gitignore: exclude scraper/scraper build artifact

docker-compose.yml

@@ -34,6 +34,7 @@ services:
         mc alias set local http://minio:9000 $${MINIO_ROOT_USER:-admin} $${MINIO_ROOT_PASSWORD:-changeme123};
         mc mb --ignore-existing local/libnovel-chapters;
         mc mb --ignore-existing local/libnovel-audio;
+        mc mb --ignore-existing local/libnovel-browse;
         echo 'buckets ready';
       "
     environment:
@@ -136,10 +137,13 @@ services:
       MINIO_USE_SSL: "false"
       MINIO_BUCKET_CHAPTERS: "${MINIO_BUCKET_CHAPTERS:-libnovel-chapters}"
       MINIO_BUCKET_AUDIO: "${MINIO_BUCKET_AUDIO:-libnovel-audio}"
+      MINIO_BUCKET_BROWSE: "${MINIO_BUCKET_BROWSE:-libnovel-browse}"
       # Public endpoint used to sign presigned audio URLs so browsers can reach them.
       # Leave empty to use MINIO_ENDPOINT (fine for local dev).
       MINIO_PUBLIC_ENDPOINT: "${MINIO_PUBLIC_ENDPOINT:-}"
       MINIO_PUBLIC_USE_SSL: "${MINIO_PUBLIC_USE_SSL:-true}"
+      # SingleFile CLI path for save-browse subcommand
+      SINGLEFILE_PATH: "${SINGLEFILE_PATH:-single-file}"
       # PocketBase
       POCKETBASE_URL: "http://pocketbase:8090"
       POCKETBASE_ADMIN_EMAIL: "${POCKETBASE_ADMIN_EMAIL:-admin@libnovel.local}"