chore: add issue forms and expand PR template (#100)

.github/pull_request_template.md

@@ -1,3 +1,36 @@
+<!--
+Thanks for contributing to SubMiner! Fill out the sections below.
+Keep it short — a couple of sentences per section is fine.
+-->
+
+## Summary
+
+<!-- What does this PR do and why? -->
+
+## Type of change
+
+<!-- Check all that apply. -->
+
+- [ ] Bug fix
+- [ ] New feature
+- [ ] Refactor / internal
+- [ ] Documentation
+- [ ] Other
+
+## Related issues
+
+<!-- e.g. "Closes #123". Delete if none. -->
+
+## How was this tested?
+
+<!--
+Describe verification. The default handoff gate is:
+  bun run typecheck && bun run test:fast && bun run test:env && bun run build && bun run test:smoke:dist
+If docs-site/ changed, also: bun run docs:test && bun run docs:build
+-->
+
 ## Checklist
 
-- [ ] Added a changelog fragment in `changes/`, or this PR is labeled `skip-changelog`
+- [ ] Added a changelog fragment, or this PR is labeled `skip-changelog` (see [`changes/README.md`](../changes/README.md))
+- [ ] Docs updated in the same PR if behavior, defaults, flags, shortcuts, ports, or APIs changed
+- [ ] Relevant checks pass locally (typecheck, tests, build)