Streamline PR template: remove CI-redundant checks, fix URL

- Remove "tests pass locally" checklist item (CI enforces this)
- Remove compiler checklist items from GPU section (CI tests these)
- Remove "Consider" profiling/scaling lines (noise for most PRs)
- Narrow GPU section trigger to src/simulation/ (only GPU-accelerated target)
- Simplify testing prompt to open-ended question
- Fix developer guide URL

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: sbryngelson

.github/pull_request_template.md

@@ -14,24 +14,19 @@ Fixes #(issue)
 
 ## Testing
 
-Describe how you tested your changes. List the compilers and platforms you used.
+How did you test your changes?
 
 ## Checklist
 
-- [ ] New and existing tests pass locally (`./mfc.sh test`)
 - [ ] I added or updated tests for new behavior
 - [ ] I updated documentation if user-facing behavior changed
 
-See the [developer guide](https://mflowcode.github.io/documentation/md_contributing.html) for full coding standards.
+See the [developer guide](https://mflowcode.github.io/documentation/contributing.html) for full coding standards.
 
 <details>
-<summary><strong>GPU changes</strong> (expand if you modified code in <code>src/</code>)</summary>
+<summary><strong>GPU changes</strong> (expand if you modified <code>src/simulation/</code>)</summary>
 
-- [ ] Code compiles with NVHPC (nvfortran)
-- [ ] Code compiles with Cray (ftn)
 - [ ] GPU results match CPU results
-- [ ] Tested on NVIDIA GPU (V100/A100/H100) or AMD GPU (MI200+)
-- [ ] Consider attaching an Nsight Systems or rocprof-systems profile if performance-sensitive
-- [ ] Consider testing with multiple GPUs (e.g. 1, 2, 8) to verify scaling
+- [ ] Tested on NVIDIA GPU or AMD GPU
 
 </details>