Remove the AI-agent workflow caller

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015XiQYLY5JBuwam5nuVnBfz

.gitea/workflows/ai-agent.yml

@@ -1,15 +0,0 @@
-name: ai-agent
-run-name: "ai-agent · #${{ github.event.issue.number }}"   # quotes required: bare # starts a YAML comment
-# Standard caller for the shared AI-agent workflow (gitea/agents). Copy this file VERBATIM into
-# any repo that should get the agents — it is identical in every repo. All logic + scripts live in
-# agents/.gitea/workflows/; scripts are fetched from @main at run time. The `jobs.agent` wrapper is
-# required: a reusable (workflow_call) workflow can only be invoked from a caller job, not top-level.
-on:
-  issue_comment:
-    types: [created]
-  issues:
-    types: [opened]
-jobs:
-  agent:
-    uses: gitea/agents/.gitea/workflows/agent.yml@main
-    secrets: inherit