feat(groups): host-based forge sources with optional display name

- forgeSources entries are now { host, type, name? }: the repository URL's
  hostname is matched case-insensitively against host (github.com for GitHub,
  distinct hosts for multiple Gitea instances); the footer label is the
  optional name, falling back to the host
- GroupEditor renders one row per source: host input + type select + optional
  display name (grid layout); hostname validation mirrors the server
- fix: apiFetch sends Content-Type: application/json — h3's readBody only
  parses JSON bodies with that header, so every PUT/POST from the refactored
  console arrived as a raw string and failed with 'groups must be an array'
- hardening: readJsonBody (admin + actions) JSON-parses string bodies so curl
  and older clients without the content-type header still work
- regression test: groups PUT without content-type + forgeSources round-trip
- docs: groups.md/message-format.md (en/zh), AGENTS.md, config.example.yaml

app/types.ts

@@ -26,6 +26,12 @@ export interface Route {
 
 export type GroupRole = "owner" | "admin" | "viewer";
 
+export interface ForgeSource {
+  host: string;
+  type: "github" | "gitea";
+  name?: string;
+}
+
 export interface GroupMember {
   login: string;
   role: GroupRole;
@@ -40,7 +46,7 @@ export interface Group {
   providers?: ("github" | "gitea" | "gitlab")[];
   installationId?: number;
   emoji?: boolean;
-  forgeLabel?: boolean;
+  forgeSources?: ForgeSource[];
   lang?: string;
   logTarget?: RouteTarget;
 }