chore: rework issue and discussion templates around scope policy

Issue forms: trim prerequisite checkboxes to the two that matter, make the
yt-dlp test field explicitly conditional (UI bugs write "UI bug"), lead the
feature form with the scope line and the already-decided list, and retire
the question template in favor of Discussions Q&A.

Discussion forms: rename q-and-a.yml to q-a.yml so it matches the actual
category slug (it never applied), add ideas.yml for the category where
feature requests actually land, drop configuration-help.yml (no matching
category) and the inert config.yml (blank_discussions_enabled is not a
GitHub feature), and remove checkboxes from low-stakes discussion forms.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

.github/ISSUE_TEMPLATE/config.yml

@@ -1,8 +1,11 @@
 blank_issues_enabled: false
 contact_links:
-  - name: MeTube Community Discussions
-    url: https://github.com/alexta69/metube/discussions
-    about: Ask questions and discuss MeTube with the community
-  - name: yt-dlp Issues
+  - name: ❓ Questions & Support
+    url: https://github.com/alexta69/metube/discussions/categories/q-a
+    about: Ask usage and configuration questions in Discussions Q&A — issues are for bugs and feature requests
+  - name: 📖 Troubleshooting FAQ
+    url: https://github.com/alexta69/metube/wiki/Troubleshooting-FAQ
+    about: Common problems and their fixes
+  - name: ⬇️ yt-dlp Issues
     url: https://github.com/yt-dlp/yt-dlp/issues
     about: Report issues related to video downloading, authentication, or site support