chore: migrate issue templates from markdown to YAML forms (#171)

Replaces placeholder-text markdown templates with structured YAML
issue forms. Dropdowns for installation method, display server, and
audio backend. Required fields for description, steps, and version.
Same output format when reading submitted issues.

cc

.github/ISSUE_TEMPLATE/feedback.yml

@@ -0,0 +1,54 @@
+name: Feedback
+description: General feedback, UX thoughts, or non-bug discussion
+title: "[Feedback] "
+labels: ["feedback"]
+body:
+  - type: textarea
+    id: feedback
+    attributes:
+      label: Feedback
+      description: Share your thoughts, impressions, or experience using QBZ.
+    validations:
+      required: true
+
+  - type: textarea
+    id: works-well
+    attributes:
+      label: What works well?
+
+  - type: textarea
+    id: improvements
+    attributes:
+      label: What could be improved?
+
+  - type: input
+    id: version
+    attributes:
+      label: QBZ version (optional)
+      placeholder: e.g. v1.1.20
+
+  - type: dropdown
+    id: install
+    attributes:
+      label: Installation method (optional)
+      options:
+        - ""
+        - AppImage
+        - .deb
+        - .rpm
+        - AUR
+        - Tarball
+        - Flatpak
+        - Built from source
+
+  - type: input
+    id: distro
+    attributes:
+      label: Distribution (optional)
+      placeholder: e.g. Arch Linux, Ubuntu 24.04
+
+  - type: textarea
+    id: notes
+    attributes:
+      label: Additional notes
+      description: Anything else you'd like to share.