secrets: distribute write-scoped Gitea PAT + homelab refresh-creds

Adds secrets/gitea-pat.yaml (SOPS-encrypted, dtoro PAT with read+write
scopes) so any enrolled client can push to dtoro/Homelab-Docs — not just
where I have SSH. Recipient set = hello.yaml's (hubris, apps, republic);
expand alongside hello.yaml when enrolling new clients.

bin/homelab gains 'refresh-creds': decrypts gitea-pat.yaml, rewrites
/etc/homelab-context/git-credentials with the write token, repoints
git's --system credential helper. Re-execs via sudo for non-root callers
(same pattern as 'homelab secret').

After this lands, 'homelab client add/remove' and wiki edits can run
from any client. The initial bootstrap still needs an operator-supplied
read-only PAT (chicken-and-egg); 'refresh-creds' upgrades the client
to write afterwards.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.sops.yaml

@@ -25,6 +25,15 @@ creation_rules:
       age1duyl8mkpgu80uv934dy8q7enqjms6yvdz264hme8uryuxmvvqesq6rusq0,
       age1vf8h7s8mqsn2q5eadgpdupsj4mwn8zguc77d85ws3xj40sl9rgksx2rxw6
 
+  - path_regex: ^secrets/gitea-pat\.yaml$
+    # Write-scoped Gitea PAT (dtoro user). Same recipient list as hello.yaml
+    # since every enrolled client should be able to push (homelab client
+    # add/remove, wiki edits, etc.).
+    age: >-
+      age1xkklkvnk5z0fsnh6cfgv70hy9ksfy8rdprwerzw4yk3p4p7cxcqs2yvpz6,
+      age1duyl8mkpgu80uv934dy8q7enqjms6yvdz264hme8uryuxmvvqesq6rusq0,
+      age1vf8h7s8mqsn2q5eadgpdupsj4mwn8zguc77d85ws3xj40sl9rgksx2rxw6
+
   - path_regex: ^secrets/gitea-tokens\.yaml$
     # Workstations only.
     age: >-