gitea forge bundle: name the parent the forge used, match protection rules as the forge does, bound a commit's size and a search's time (issue 539)

The forge's contents and diffpatch endpoints take a branch, never a commit to
build on, so the parent is read from the commit the forge made, and a branch
that moved under the commit is said. Blobs are read at the commit read first,
not at the branch name. Protection rules match as Gitea 1.27 matches them
([...], {a,b}, escapes, a plain name in any case), in the Go bundle and in
guard.ts alike. One commit carries at most 4 MiB per file or patch and 16 MiB
together; code search stops at its deadline and says so. The HTTP client the
two Go bundles copied is one package, internal/forgehttp.

modules/gitea/cmd/npm-registry/retention_test.go

@@ -15,6 +15,8 @@ import (
 	"sync"
 	"testing"
 	"time"
+
+	"gitea/internal/forgehttp"
 )
 
 // fakeForge answers the forge's interface from maps, and records every delete.
@@ -38,7 +40,7 @@ func (f *fakeForge) serve() *Forge {
 	if err := os.WriteFile(file, []byte(f.password+"\n"), 0o600); err != nil {
 		f.t.Fatal(err)
 	}
-	return &Forge{URL: srv.URL, User: "admin", PasswordFile: file, Owner: "acme"}
+	return &Forge{Client: forgehttp.Client{URL: srv.URL, User: "admin", PasswordFile: file}, Owner: "acme"}
 }
 
 var (
@@ -501,7 +503,7 @@ func TestAnAnswerTheCapCutIsRefused(t *testing.T) {
 	if err := os.WriteFile(file, []byte("x\n"), 0o600); err != nil {
 		t.Fatal(err)
 	}
-	f := &Forge{URL: srv.URL, User: "admin", PasswordFile: file, Owner: "acme"}
+	f := &Forge{Client: forgehttp.Client{URL: srv.URL, User: "admin", PasswordFile: file}, Owner: "acme"}
 	if _, err := f.do(context.Background(), http.MethodGet, "/big"); err == nil || !strings.Contains(err.Error(), "not read whole") {
 		t.Fatalf("a cut answer: %v", err)
 	}