fix(ci): restrict workflow to PRs and improve release tagging

Restrict the CI pipeline to pull request events only by removing the unconfigured push trigger and eliminating a duplicate pull_request block in the workflow file. Update the Makefile to suppress stderr from the aichat command and introduce a fallback release tag message for robust version tagging. Additionally, bump the obikmer crate version to 1.1.19.

.gitea/workflows/ci.yml

@@ -1,9 +1,8 @@
 name: CI
 
 on:
-  push:
-    branches: ['main']
   pull_request:
+    branches: ['main']
 
 jobs:
   build: