Replace Python CLI with Gitea issue tracker setup

Switch from a custom CLI ticketing tool to Gitea-native issue tracking.
Add issue templates (bug, feature, task) and a curated initial backlog
of 20 tickets covering project foundation, testing, security, docs,
features, and community maintenance.

.gitea/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,10 @@
+blank_issues_enabled: true
+
+contact_links:
+  - name: "❓ Ask a Question"
+    url: https://gitea.arcline-project.local/
+    about: "Use the discussions or chat instead."
+  - name: "📖 Project Docs"
+    url: https://docs.arcline-project.local/
+    about: "Read the documentation before filing an issue."
+