docs(discussions): simplify q-and-a template

Problem
- The current discussion templates are broader than needed for this branch
- The Q&A form asks for overlapping information and treats software-specific details as too central

Change
- keep only the Q&A discussion template
- make most fields optional and clarify that users should fill them only when relevant
- align field labels with the existing issue templates where practical
- merge the latest upstream master into the branch

Authored by OpenClaw (model: gpt-5.4)

Author: njzjz-bot

.github/DISCUSSION_TEMPLATE/README.md

@@ -2,14 +2,12 @@
 
 This directory contains GitHub Discussion category forms for DeePMD-kit.
 
-## Active templates
+## Active template
 
-- `general.yml` → **General**
 - `q-a.yml` → **Q&A**
-- `ideas.yml` → **Ideas**
-- `show-and-tell.yml` → **Show and tell**
 
 ## Notes
 
-GitHub Discussion form filenames must match the target discussion category slug exactly.
-Top-level keys allowed by GitHub are limited; use `title`, `labels`, and `body`.
+- The filename must match the discussion category slug exactly.
+- GitHub Discussion forms only support a limited set of top-level keys, such as `title`, `labels`, and `body`.
+- This Q&A template is intentionally lightweight; most fields are optional and should be filled only when relevant.