fork: add Gitea/Forgejo source support for company skills

Reintroduce Gitea/Forgejo as a skill import source on dev only, since
the fork deploys against git.farh.net. Pasting a Gitea/Forgejo repo
URL into the skills sidebar mirrors the existing GitHub experience:
pin to a commit SHA, check for updates, read repo files.

Server: new gitea-fetch.ts (URL builders, probe-cache helpers) and
gitea-skills.ts (parse, probe, pin, tree, text, branch). Dispatch in
readUrlSkillImports probes /api/v1/version and routes non-github.com
hosts into the new readGiteaUrlSkillImports branch. updateStatus and
readFile get a gitea arm alongside the github/skills_sh arm. Audit
falls through to "remote not supported" the same way github does.

UI: Server icon, Gitea source label, gitea in the "external" source
class, Pin/Update UI gate widened to sourceType === "gitea". CLI help
text updated. Existing github code is left byte-for-byte unchanged
(wrapped in isGitHubDotCom) so dev <-> master syncs stay clean.

PAT support, gitea portability descriptors, and gitea audit are
deliberate follow-ups. Detection requires /api/v1/version to return
Gitea-shaped JSON; the per-host result is cached for process lifetime
with FIFO eviction at 1024 entries. Non-Gitea hosts fall through to
the existing raw-markdown url branch.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

cli/src/commands/client/skills.ts

@@ -255,7 +255,7 @@ export function registerSkillsCommands(program: Command): void {
   addCommonClientOptions(
     skills
       .command("import")
-      .description("Import company skills from a local path, GitHub, skills.sh, or URL source")
+      .description("Import company skills from a local path, GitHub, Gitea/Forgejo, skills.sh, or URL source")
       .argument("<source>", "Skill source")
       .action(async (source: string, opts: SkillsOptions) => {
         try {