feat(groups): optional forge source label in message footers

- Group.forgeLabel (default off, editable per group in the console) shows the
  source forge on every message the group's routes dispatch
- Discord embed footer: forge name next to the repo + the site's favicon as
  icon_url (Gitea instance's own favicon from its origin)
- Telegram footer: hyperlinked site name (GitHub or Gitea hostname); custom
  webhooks render a plain 'Custom' label
- forgeInfo() derives branding from event.provider + repository.html_url;
  dispatch attaches it to the NeutralMessage like mentionRoleIds
- validateGroups accepts forgeLabel booleans; GroupEditor gains the toggle
- tests: forgeInfo unit, discord/telegram footer render, dispatch on/off
- docs: groups.md + message-format.md (en/zh), config.example.yaml, AGENTS.md
- fix: wrangler.jsonc compatibility_date was an incomplete '2026-'

tests/formatter.test.ts

@@ -1,6 +1,6 @@
 import { describe, it, expect } from "bun:test";
 import { formatEvent } from "../server/lib/formatters";
-import { MAX_COMMIT_SUBJECT } from "../server/lib/formatters/helpers";
+import { forgeInfo, MAX_COMMIT_SUBJECT } from "../server/lib/formatters/helpers";
 import type { Route, WebhookEvent } from "../server/lib/types";
 
 const route: Route = {
@@ -518,3 +518,38 @@ describe("limits and localization", () => {
     expect(msg.description!.length).toBe(4096);
   });
 });
+
+describe("forge source branding", () => {
+  it("github events brand as GitHub with the favicon", () => {
+    expect(
+      forgeInfo({ event: "push", provider: "github", payload: {} }),
+    ).toEqual({
+      name: "GitHub",
+      url: "https://github.com",
+      iconUrl: "https://github.com/favicon.ico",
+    });
+  });
+
+  it("gitea events brand as the instance hostname derived from the repo url", () => {
+    expect(
+      forgeInfo({
+        event: "push",
+        provider: "gitea",
+        payload: { repository: { html_url: "https://git.example.com/org/repo" } },
+      }),
+    ).toEqual({
+      name: "git.example.com",
+      url: "https://git.example.com",
+      iconUrl: "https://git.example.com/favicon.ico",
+    });
+    expect(
+      forgeInfo({ event: "push", provider: "gitea", payload: {} }),
+    ).toBeUndefined();
+  });
+
+  it("custom events brand as a plain label without links", () => {
+    expect(forgeInfo({ event: "custom", provider: "custom", payload: {} })).toEqual({
+      name: "Custom",
+    });
+  });
+});