feat(issue-forms): add 'Troubleshooting already attempted' checklist to bug report

Harvested from idaptik's local bug form (generalised from web-specific to
estate-generic) during the issue-template unification audit. Makes the canon
bug form a strict upgrade over every local override before they're retired to
inherit it.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: hyperpolymath

.github/ISSUE_TEMPLATE/01-bug_report.yml

@@ -98,6 +98,21 @@ body:
       validations:
         required: false
 
+  - type: checkboxes
+    id: troubleshooting
+    attributes:
+      label: Troubleshooting already attempted
+      description: Tick anything you've already tried — it narrows the cause and avoids back-and-forth.
+      options:
+        - label: Reproduced on the latest `main` (not a stale checkout).
+          required: false
+        - label: Tried a clean rebuild / cleared caches / fresh environment.
+          required: false
+        - label: Reproduced with a minimal config or default settings.
+          required: false
+        - label: Checked the README, CHANGELOG, and existing docs.
+          required: false
+
   - type: checkboxes
     id: checklist
     attributes: