chore(github): add issue templates (bug / feature / question)

YAML issue forms with required fields so new reports arrive with the
context needed to act on them (version, OS, reproduction steps for
bugs; problem-before-solution for features). Auto-applies the matching
label.

blank_issues_enabled: false forces use of one of the three templates.
config.yml also surfaces the Patreon link as a contact option.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.github/ISSUE_TEMPLATE/bug_report.yml

@@ -0,0 +1,90 @@
+name: Bug report
+description: Something is broken or behaves unexpectedly.
+title: "[Bug]: "
+labels: ["bug"]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Thanks for taking the time to report a bug. The clearer the
+        reproduction, the faster it gets fixed.
+
+        Before filing, please check the [existing issues](https://github.com/HakanSeven12/OpenCADStudio/issues?q=is%3Aissue)
+        in case it's already reported.
+
+  - type: textarea
+    id: summary
+    attributes:
+      label: Summary
+      description: One or two sentences describing what's wrong.
+      placeholder: e.g. "FILLET command doesn't switch to select mode after picking the first line."
+    validations:
+      required: true
+
+  - type: textarea
+    id: steps
+    attributes:
+      label: Steps to reproduce
+      description: Numbered, minimal steps a stranger can follow.
+      placeholder: |
+        1. Open `attached.dwg`
+        2. Type `FILLET`, press Enter
+        3. Click line A
+        4. Expected: command waits for line B. Actual: command ends.
+    validations:
+      required: true
+
+  - type: textarea
+    id: expected
+    attributes:
+      label: Expected behaviour
+    validations:
+      required: true
+
+  - type: textarea
+    id: actual
+    attributes:
+      label: Actual behaviour
+      description: What happened instead. Include error messages and screenshots / screen recordings if it's visual.
+    validations:
+      required: true
+
+  - type: input
+    id: version
+    attributes:
+      label: Open CAD Studio version
+      description: Visible in About / titlebar. e.g. `0.4.0`
+      placeholder: "0.4.0"
+    validations:
+      required: true
+
+  - type: dropdown
+    id: os
+    attributes:
+      label: Operating system
+      options:
+        - Windows
+        - Linux
+        - macOS
+        - Other (please specify in Additional context)
+    validations:
+      required: true
+
+  - type: textarea
+    id: file
+    attributes:
+      label: Sample drawing
+      description: |
+        If the bug only reproduces with a specific file, attach a minimal
+        DWG/DXF that triggers it. Drag-and-drop into the comment box —
+        GitHub will host the attachment.
+    validations:
+      required: false
+
+  - type: textarea
+    id: context
+    attributes:
+      label: Additional context
+      description: Logs, related issues, anything else that might help.
+    validations:
+      required: false