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)

cmd/server/main.go

@@ -0,0 +1,22 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"net/http"
+
+	_ "goyomi/internal/registry" // ensures registry package is initialized
+)
+
+func main() {
+	mux := http.NewServeMux()
+	mux.HandleFunc("/healthz", func(w http.ResponseWriter, r *http.Request) {
+		fmt.Fprintln(w, "ok")
+	})
+
+	addr := ":8080"
+	log.Printf("listening on %s", addr)
+	if err := http.ListenAndServe(addr, mux); err != nil {
+		log.Fatal(err)
+	}
+}