feat: initial Phase 1 implementation — core framework + Docker

- Data types (SManga, SChapter, Page, MangasPage, all Filter variants)
- Source interfaces (Source, CatalogueSource) with MD5-based ID generation matching Tachiyomi/Suwayomi
- HTTP client with per-host rate limiting, cookie jar, and 429 retry
- FlareSolverr v1 client (FLARESOLVERR_URL env)
- Generic GraphQL POST helper
- goquery HTML parser wrappers
- Source registry (panics on duplicate ID)
- Multi-stage Dockerfile (golang:1.26-alpine + distroless) and compose.yml (postgres, flaresolverr, app)

internal/source/interfaces.go

@@ -0,0 +1,59 @@
+package source
+
+import (
+	"crypto/md5"
+	"strings"
+)
+
+// Source is the base interface for all sources.
+type Source interface {
+	ID() int64
+	Name() string
+	Lang() string
+}
+
+// CatalogueSource is the full interface every source must implement.
+type CatalogueSource interface {
+	Source
+	SupportsLatest() bool
+	GetPopularManga(page int) (MangasPage, error)
+	GetLatestUpdates(page int) (MangasPage, error)
+	GetSearchManga(page int, query string, filters []Filter) (MangasPage, error)
+	GetMangaDetails(manga SManga) (SManga, error)
+	GetChapterList(manga SManga) ([]SChapter, error)
+	GetPageList(chapter SChapter) ([]Page, error)
+	// GetImageURL resolves the final image URL for a page.
+	// Sources that embed image URLs directly in pages return page.ImageURL unchanged.
+	GetImageURL(page Page) (string, error)
+	GetFilterList() []Filter
+}
+
+// GenerateSourceID replicates Tachiyomi/Suwayomi HttpSource.generateId:
+//
+//	key = "${name.lowercase()}/$lang/$versionId"
+//	MD5(key) → first 8 bytes as big-endian int64, sign bit cleared (& Long.MAX_VALUE)
+func GenerateSourceID(name, lang string) int64 {
+	return GenerateSourceIDv(name, lang, 1)
+}
+
+func GenerateSourceIDv(name, lang string, versionID int) int64 {
+	key := strings.ToLower(name) + "/" + lang + "/" + itoa(versionID)
+	b := md5.Sum([]byte(key))
+	var id int64
+	for i := 0; i < 8; i++ {
+		id |= int64(b[i]) << (8 * (7 - i))
+	}
+	return id & int64(^uint64(0)>>1) // clear sign bit (& Long.MAX_VALUE)
+}
+
+func itoa(n int) string {
+	if n == 0 {
+		return "0"
+	}
+	digits := []byte{}
+	for n > 0 {
+		digits = append([]byte{byte('0' + n%10)}, digits...)
+		n /= 10
+	}
+	return string(digits)
+}