chore: add issue and pull request templates

Public contributors need a clear intake path for bugs, website change requests, and pull requests.

The templates ask for maintainer review context without making the PR form heavy.

Constraint: Templates should stay lightweight for OSS contributors
Rejected: Large PR checkbox grid | too much friction for small website changes
Confidence: high
Scope-risk: narrow
Reversibility: clean
Tested: pnpm format; pnpm lint; pnpm typecheck; pnpm spell
Tested: pnpm test; pnpm build; YAML parse for issue forms
Tested: pnpm exec playwright test --project=firefox --reporter=list
Not-tested: GitHub rendered form preview

Author: taroj1205

.github/ISSUE_TEMPLATE/bug_report.yml

@@ -0,0 +1,87 @@
+name: Bug report
+description: Report a problem on the Zen Browser website
+title: "[Bug]: "
+labels: ["bug"]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Thanks for reporting a website issue. Please include enough detail for maintainers to reproduce it.
+
+        Please search open and closed issues before submitting. Someone might have reported the same thing already.
+
+  - type: input
+    id: page
+    attributes:
+      label: Affected page
+      description: Paste the URL or route where the issue appears.
+      placeholder: "https://zen-browser.app/download"
+    validations:
+      required: true
+
+  - type: textarea
+    id: problem
+    attributes:
+      label: What happened?
+      description: Describe the visible problem or broken behavior.
+    validations:
+      required: true
+
+  - type: textarea
+    id: expected
+    attributes:
+      label: Expected behavior
+    validations:
+      required: true
+
+  - type: textarea
+    id: reproduce
+    attributes:
+      label: Steps to reproduce
+      placeholder: |
+        1. Open ...
+        2. Click ...
+        3. See ...
+    validations:
+      required: true
+
+  - type: dropdown
+    id: area
+    attributes:
+      label: Area
+      options:
+        - Home / marketing pages
+        - Download page
+        - Release notes / what's new
+        - Mods pages
+        - Navigation / layout
+        - Translations
+        - Build / CI
+        - Other
+    validations:
+      required: true
+
+  - type: input
+    id: browser
+    attributes:
+      label: Browser and device
+      placeholder: "Firefox 145 on macOS, Safari on iPhone, etc."
+
+  - type: checkboxes
+    id: ai_use
+    attributes:
+      label: AI use
+      options:
+        - label: I did not use AI to create this issue.
+        - label: If there is no check above, I reviewed the generated content before submitting.
+
+  - type: textarea
+    id: screenshots
+    attributes:
+      label: Screenshots or recordings
+      description: Drag screenshots, videos, or logs here if useful.
+
+  - type: textarea
+    id: extra
+    attributes:
+      label: Additional context

.github/ISSUE_TEMPLATE/change_request.yml

@@ -0,0 +1,64 @@
+name: Website change request
+description: Suggest a content, UI, translation, or website improvement
+title: "[Change]: "
+labels: ["enhancement"]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Thanks for suggesting a website improvement.
+
+        Please search open and closed issues before submitting. Someone might have requested the same thing already.
+
+  - type: dropdown
+    id: area
+    attributes:
+      label: Area
+      options:
+        - Content / copy
+        - UI / visual design
+        - Download page
+        - Release notes / what's new
+        - Mods pages
+        - Translations
+        - Accessibility
+        - Build / tooling
+        - Other
+    validations:
+      required: true
+
+  - type: input
+    id: page
+    attributes:
+      label: Related page or route
+      placeholder: "https://zen-browser.app/..."
+
+  - type: textarea
+    id: proposal
+    attributes:
+      label: Proposed change
+      description: What should change?
+    validations:
+      required: true
+
+  - type: textarea
+    id: reason
+    attributes:
+      label: Why is this useful?
+      description: Explain the user-facing benefit or problem this solves.
+    validations:
+      required: true
+
+  - type: checkboxes
+    id: ai_use
+    attributes:
+      label: AI use
+      options:
+        - label: I did not use AI to create this issue.
+        - label: If there is no check above, I reviewed the generated content before submitting.
+
+  - type: textarea
+    id: details
+    attributes:
+      label: Implementation notes
+      description: Optional screenshots, copy suggestions, links, or technical details.

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,5 @@
+blank_issues_enabled: false
+contact_links:
+  - name: Contributing guide
+    url: https://docs.zen-browser.app/contribute/www
+    about: Read this before opening a contribution PR.

.github/pull_request_template.md

@@ -0,0 +1,26 @@
+## Related issue
+
+<!-- Use "Closes #123", "Fixes #123", "Related #123", or "No linked issue". -->
+
+## Summary
+
+<!-- What changed, and why? Keep this short. -->
+
+## Affected area
+
+<!-- Example: home page, download page, release notes, mods, navigation, translations, tests, CI. -->
+
+## Screenshots or preview
+
+<!-- Required for visible UI changes. Add before/after screenshots, recordings, or a preview URL. -->
+
+## AI use
+
+<!-- Disclose AI-assisted code, copy, translations, screenshots, or other submitted content. -->
+
+- [ ] No AI tools were used.
+- [ ] AI tools were used, and I reviewed the output for accuracy, licensing, and project fit.
+
+## Verification
+
+<!-- List the commands or checks you ran. -->