Add CI release workflow, CHANGELOG.md, issue templates

- .github/workflows/release.yml: on tag push, build exe via ps2exe,
  package portable zip, attach SHA-256, create GitHub Release.
- CHANGELOG.md: Keep a Changelog format, semver.
- .github/ISSUE_TEMPLATE/: bug_report.yml + feature_request.yml + config.yml
  routing security reports to private advisories.

.github/ISSUE_TEMPLATE/bug_report.yml

@@ -0,0 +1,55 @@
+name: Bug report
+description: Something doesn't work as expected
+labels: ["bug"]
+body:
+  - type: input
+    id: version
+    attributes:
+      label: Version
+      description: Visible in the startup banner.
+      placeholder: v1.0.0
+    validations:
+      required: true
+
+  - type: textarea
+    id: steps
+    attributes:
+      label: Steps to reproduce
+      placeholder: |
+        1. ...
+        2. ...
+        3. ...
+    validations:
+      required: true
+
+  - type: textarea
+    id: expected
+    attributes:
+      label: What you expected to happen
+    validations:
+      required: true
+
+  - type: textarea
+    id: actual
+    attributes:
+      label: What actually happened
+      description: Paste any error output verbatim. Screenshots are welcome.
+    validations:
+      required: true
+
+  - type: input
+    id: os
+    attributes:
+      label: Windows version
+      placeholder: e.g. Windows 11 24H2
+
+  - type: input
+    id: adapter
+    attributes:
+      label: Adapter (if relevant)
+      placeholder: e.g. Realtek USB GbE Family Controller
+
+  - type: textarea
+    id: extra
+    attributes:
+      label: Anything else?