fix(formatters): use raster PNG forge icons Discord renders

- GitHub footer icon now uses fluidicon.png instead of favicon.ico —
  Discord silently drops .ico embed footer icons (png/jpg/webp/gif only)
- Gitea instances use {origin}/assets/img/favicon.png (verified on
  codeberg.org and gitea.com); links are still derived from the repo URL
- tests + docs updated to the new icon URLs

tests/discord.test.ts

@@ -91,12 +91,12 @@ describe("discord role mentions", () => {
       forge: {
         name: "GitHub",
         url: "https://github.com",
-        iconUrl: "https://github.com/favicon.ico",
+        iconUrl: "https://github.com/fluidicon.png",
       },
     });
     expect(out.embeds?.[0]?.footer).toEqual({
       text: "GitHub · acme/widget",
-      icon_url: "https://github.com/favicon.ico",
+      icon_url: "https://github.com/fluidicon.png",
     });
   });
 });
@@ -451,7 +451,7 @@ describe("dispatchEvent fallback routing", () => {
     });
     expect(footers).toContainEqual({
       text: "内网 Gitea · owner/repo",
-      icon_url: "https://git.example.com/favicon.ico",
+      icon_url: "https://git.example.com/assets/img/favicon.png",
     });
     expect(footers).toContainEqual({ text: "owner/repo" });
   });

tests/formatter.test.ts

@@ -535,7 +535,7 @@ describe("forge source branding", () => {
     ).toEqual({
       name: "github.com",
       url: "https://github.com",
-      iconUrl: "https://github.com/favicon.ico",
+      iconUrl: "https://github.com/fluidicon.png",
     });
   });
 
@@ -543,7 +543,7 @@ describe("forge source branding", () => {
     expect(forgeInfo({ event: "ping", provider: "github", payload: {} }, [ghHost])).toEqual({
       name: "github.com",
       url: "https://github.com",
-      iconUrl: "https://github.com/favicon.ico",
+      iconUrl: "https://github.com/fluidicon.png",
     });
   });
 
@@ -564,7 +564,7 @@ describe("forge source branding", () => {
     ).toEqual({
       name: "git1.example.com",
       url: "https://git1.example.com",
-      iconUrl: "https://git1.example.com/favicon.ico",
+      iconUrl: "https://git1.example.com/assets/img/favicon.png",
     });
     expect(
       forgeInfo(
@@ -578,7 +578,7 @@ describe("forge source branding", () => {
     ).toEqual({
       name: "git2.example.com",
       url: "https://git2.example.com",
-      iconUrl: "https://git2.example.com/favicon.ico",
+      iconUrl: "https://git2.example.com/assets/img/favicon.png",
     });
   });
 
@@ -599,7 +599,7 @@ describe("forge source branding", () => {
     ).toEqual({
       name: "内网 Gitea",
       url: "https://git1.example.com",
-      iconUrl: "https://git1.example.com/favicon.ico",
+      iconUrl: "https://git1.example.com/assets/img/favicon.png",
     });
     expect(
       forgeInfo(
@@ -613,7 +613,7 @@ describe("forge source branding", () => {
     ).toEqual({
       name: "git2.example.com",
       url: "https://git2.example.com",
-      iconUrl: "https://git2.example.com/favicon.ico",
+      iconUrl: "https://git2.example.com/assets/img/favicon.png",
     });
     expect(
       forgeInfo(
@@ -627,7 +627,7 @@ describe("forge source branding", () => {
     ).toEqual({
       name: "git1.example.com",
       url: "https://git1.example.com",
-      iconUrl: "https://git1.example.com/favicon.ico",
+      iconUrl: "https://git1.example.com/assets/img/favicon.png",
     });
   });
 
@@ -644,7 +644,7 @@ describe("forge source branding", () => {
     ).toEqual({
       name: "Git1.Example.com",
       url: "https://git1.example.com",
-      iconUrl: "https://git1.example.com/favicon.ico",
+      iconUrl: "https://git1.example.com/assets/img/favicon.png",
     });
   });