feat(github): minimal bug-report issue form (#1100)

One required textarea plus four one-click fields: version (plannotator
--version), OS, agent, surface. Feature requests stay blank issues.

Claude-Session: https://claude.ai/code/session_01YXkgsNucxDwAL4GdR4XYRk

.github/ISSUE_TEMPLATE/bug-report.yml

@@ -0,0 +1,61 @@
+name: Bug report
+description: Something broke or didn't behave as expected
+body:
+  - type: textarea
+    id: what-happened
+    attributes:
+      label: What happened?
+      description: What did you do, what did you expect, what happened instead. Screenshots welcome.
+    validations:
+      required: true
+  - type: input
+    id: version
+    attributes:
+      label: Plannotator version
+      description: Paste the output of `plannotator --version`
+      placeholder: plannotator 0.24.1
+    validations:
+      required: true
+  - type: dropdown
+    id: os
+    attributes:
+      label: OS
+      options:
+        - macOS
+        - Linux
+        - Windows
+        - Devcontainer / SSH / remote
+    validations:
+      required: true
+  - type: dropdown
+    id: agent
+    attributes:
+      label: Agent
+      description: Which coding agent were you using Plannotator with?
+      options:
+        - Claude Code
+        - OpenCode
+        - Pi
+        - Codex
+        - Amp
+        - Droid
+        - Copilot CLI
+        - Gemini CLI
+        - Kiro CLI
+        - None / standalone CLI
+        - Other
+    validations:
+      required: true
+  - type: dropdown
+    id: surface
+    attributes:
+      label: Where did it happen?
+      options:
+        - Plan review
+        - Code review
+        - Annotate
+        - Install / CLI
+        - VS Code extension
+        - Other
+    validations:
+      required: true

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,5 @@
+blank_issues_enabled: true
+contact_links:
+  - name: Feature request or idea
+    url: https://github.com/backnotprop/plannotator/issues/new
+    about: No form needed. Open a blank issue and describe what you want.