chore: improve issue and PR templates with industry best practices (#1088)

Bug report template:
- Add OS, Node.js version, shell, and install method fields
- Add all 6 supported runtimes (+ Multiple option)
- Add frequency and severity/impact dropdowns
- Add config.json, STATE.md, and settings.json retrieval instructions
- Add PII warnings on every field that could leak sensitive data
- Recommend presidio-anonymizer and scrub for log anonymization
- Add diagnostic commands for debugging install issues
- Add mandatory PII review checklist checkbox

Feature request template:
- Add scope dropdown (core workflow, planning, context, runtime, etc.)
- Add runtime multi-select checkboxes

New templates:
- Documentation issue template (incorrect, missing, unclear, outdated)
- config.yml to disable blank issues and link Discord/Discussions

PR template:
- Add linked issue reference (Closes #)
- Add How section for approach description
- Add runtime testing checklist (all 5 runtimes + N/A)
- Add template/reference update check
- Add test pass check
- Add screenshots/recordings section

.github/pull_request_template.md

@@ -6,11 +6,32 @@
 
 <!-- One sentence: why is this change needed? -->
 
+Closes #<!-- issue number -->
+
+## How
+
+<!-- Brief description of the approach taken. Skip for trivial changes. -->
+
 ## Testing
 
-- [ ] Tested on macOS
-- [ ] Tested on Windows
-- [ ] Tested on Linux
+### Platforms tested
+
+- [ ] macOS
+- [ ] Windows (including backslash path handling)
+- [ ] Linux
+
+### Runtimes tested
+
+- [ ] Claude Code
+- [ ] Gemini CLI
+- [ ] OpenCode
+- [ ] Codex
+- [ ] Copilot
+- [ ] N/A (not runtime-specific)
+
+### Test details
+
+<!-- How did you verify this works? Manual steps, automated tests, etc. -->
 
 ## Checklist
 
@@ -18,7 +39,15 @@
 - [ ] Updates CHANGELOG.md for user-facing changes
 - [ ] No unnecessary dependencies added
 - [ ] Works on Windows (backslash paths tested)
+- [ ] Templates/references updated if behavior changed
+- [ ] Existing tests pass (`npm test`)
 
 ## Breaking Changes
 
+<!-- List any breaking changes, or write "None" -->
+
 None
+
+## Screenshots / recordings
+
+<!-- If this is a visual change, add before/after screenshots. Delete this section if not applicable. -->