docs: add bug report issue template

Adds a structured GitHub issue form for bug reports with environment
details and a prefilled description guiding reporters to include
expected behavior, actual behavior, and logs.

Co-Authored-By: Claude <claude@anthropic.com>
Closes: #967
Signed-off-by: Ryan Petrello <rpetrell@redhat.com>

Author: ryanpetrello

.github/ISSUE_TEMPLATE/bug_report.yml

@@ -0,0 +1,33 @@
+name: Bug Report
+description: Report a bug in fromager
+labels: ["bug"]
+title: "[Bug]: "
+body:
+  - type: textarea
+    id: environment
+    attributes:
+      label: Environment
+      description: Details about your build environment.
+      value: |
+        - Fromager version:
+        - Python version:
+        - OS / architecture:
+        - Container or local:
+    validations:
+      required: true
+
+  - type: textarea
+    id: bug-description
+    attributes:
+      label: Bug description
+      description: Describe the bug you encountered.
+      value: |
+        **Expected behavior:**
+
+
+        **Actual behavior:**
+
+
+        **Steps to reproduce / logs:**
+    validations:
+      required: true