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/parser/html.go

@@ -0,0 +1,67 @@
+package parser
+
+import (
+	"net/http"
+	"net/url"
+	"strings"
+
+	"github.com/PuerkitoBio/goquery"
+)
+
+func Parse(html string) (*goquery.Document, error) {
+	return goquery.NewDocumentFromReader(strings.NewReader(html))
+}
+
+func ParseResponse(resp *http.Response) (*goquery.Document, error) {
+	defer resp.Body.Close()
+	return goquery.NewDocumentFromReader(resp.Body)
+}
+
+func Select(doc *goquery.Document, css string) *goquery.Selection {
+	return doc.Find(css)
+}
+
+func SelectFrom(sel *goquery.Selection, css string) *goquery.Selection {
+	return sel.Find(css)
+}
+
+func Attr(sel *goquery.Selection, name string) string {
+	val, _ := sel.Attr(name)
+	return val
+}
+
+// AbsURL resolves a relative URL attribute against baseURL.
+func AbsURL(sel *goquery.Selection, attr string, baseURL string) string {
+	val := Attr(sel, attr)
+	if val == "" {
+		return ""
+	}
+	base, err := url.Parse(baseURL)
+	if err != nil {
+		return val
+	}
+	ref, err := url.Parse(val)
+	if err != nil {
+		return val
+	}
+	return base.ResolveReference(ref).String()
+}
+
+// OwnText returns the text content of the element excluding child elements.
+func OwnText(sel *goquery.Selection) string {
+	clone := sel.Clone()
+	clone.Children().Remove()
+	return strings.TrimSpace(clone.Text())
+}
+
+func TextTrim(sel *goquery.Selection) string {
+	return strings.TrimSpace(sel.Text())
+}
+
+func First(sel *goquery.Selection) *goquery.Selection {
+	return sel.First()
+}
+
+func Each(sel *goquery.Selection, fn func(i int, s *goquery.Selection)) {
+	sel.Each(fn)
+}