Fix Gitea pipelines to use authenticated tea CLI without --login flag

Remove redundant --login librete flags from all gt-* pipeline tea commands since
authentication is already configured via tea logins. This simplifies the commands
and prevents potential authentication issues.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

.wave/pipelines/gt-issue-update.yaml

@@ -35,7 +35,7 @@ steps:
         1. tea --version
 
         2. Fetch the full issue:
-           tea issues list --repo REPO --login librete -o json -f index,title,body,labels,state,url --limit 50
+           tea issues list --repo REPO -o json -f index,title,body,labels,state,url --limit 50
            Then filter the JSON for the issue matching NUMBER.
 
         3. Get commits since the issue was created (cap at 100):
@@ -147,14 +147,14 @@ steps:
 
         Step 3: Apply the update:
         - If title_changed is true:
-          tea issues edit <NUMBER> --repo <REPO> --login librete -t "<updated_title>"
+          tea issues edit <NUMBER> --repo <REPO> -t "<updated_title>"
         - Write the updated_body to a temp file, then apply it:
           Write updated_body to /tmp/issue-body.md
-          tea issues edit <NUMBER> --repo <REPO> --login librete -d "$(cat /tmp/issue-body.md)"
+          tea issues edit <NUMBER> --repo <REPO> -d "$(cat /tmp/issue-body.md)"
         - Clean up /tmp/issue-body.md after applying.
 
         Step 4: Verify the update was applied:
-        tea issues list --repo <REPO> --login librete -o json -f index,title,body,url --limit 50
+        tea issues list --repo <REPO> -o json -f index,title,body,url --limit 50
         Then filter for the specific issue number.
 
         Compare the returned title and body against what was intended. Flag any discrepancies.