fix(ci): use GPT-6 Luna for issue automation (#51261)

Co-authored-by: rekram1-node <rekram1-node@users.noreply.github.com>

.github/workflows/duplicate-issues.yml

@@ -54,7 +54,7 @@ jobs:
               "webfetch": "deny"
             }
         run: |
-          opencode run -m opencode/claude-sonnet-4-6 "A new issue has been created:
+          opencode run -m opencode/gpt-6-luna --variant high "A new issue has been created:
 
           Issue number: ${{ github.event.issue.number }}
           Issue author association: ${{ github.event.issue.author_association }}
@@ -188,7 +188,7 @@ jobs:
               "webfetch": "deny"
             }
         run: |
-          opencode run -m opencode/claude-sonnet-4-6 "Issue #${{ github.event.issue.number }} was previously flagged as non-compliant and has been edited.
+          opencode run -m opencode/gpt-6-luna --variant high "Issue #${{ github.event.issue.number }} was previously flagged as non-compliant and has been edited.
           Issue author association: ${{ github.event.issue.author_association }}
 
           Lookup this issue with gh issue view ${{ github.event.issue.number }}.

.github/workflows/triage.yml

@@ -49,7 +49,7 @@ jobs:
           ISSUE_TITLE: ${{ github.event.issue.title }}
           ISSUE_BODY: ${{ github.event.issue.body }}
         run: |
-          opencode run --agent triage "The following issue was just opened, triage it:
+          opencode run --agent triage --variant high "The following issue was just opened, triage it:
 
           Title: $ISSUE_TITLE