docs: add a performance report issue form and ask for summary lines

.github/ISSUE_TEMPLATE/performance.yml asks for the title and scene, what is
slow or what changed, the summary lines and traces of APS5_TRACE_FRAMES
captures, the trace digest and optionally the worker's collapsed stacks,
and states the capture protocol: warm caches, the same scene and settings,
no other profiling switch, the same machine and session. The pull request
template and CONTRIBUTING ask a pull request that claims a change in speed
for the summary lines of main and of the change, captured the same way.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.github/ISSUE_TEMPLATE/performance.yml

@@ -0,0 +1,65 @@
+name: Performance report
+description: A slow scene or a change in speed, measured with a performance trace so that reports can be compared.
+title: "perf: "
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Capture the scene with `APS5_TRACE_FRAMES=<start>:<count>` (presents; `APS5_TRACE_SECONDS=<start>:<length>` also works), as described under [Performance trace](https://github.com/boykopovar/AnyPS5/blob/main/docs/dev/BUILD.md#performance-trace). It writes `aps5-trace-<commit>-<pid>.json.gz` and appends one line to `aps5-summary.jsonl`.
+
+        - Run the scene once and restart the title, so the shader and pipeline caches are warm.
+        - Use the same scene, window, resolution and settings for every capture you compare.
+        - Set no other `APS5_TRACE_*` or `APS5_PROFILE_*` switch and do not redirect the log; they cost time.
+        - Capture the base and the change on the same machine in the same session.
+
+        A trace holds timings, scope and thread names and counts, no game data. The summary line names the GPU, driver and OS.
+  - type: input
+    id: scene
+    attributes:
+      label: Title and scene
+      description: Title ID and what the window covers (menu, level, position, cutscene).
+      placeholder: PPSA01325, main menu after the intro
+    validations:
+      required: true
+  - type: textarea
+    id: observed
+    attributes:
+      label: What is slow or what changed
+      description: What you see (frame time, stutter, a phase that grew) and, for a comparison, the two commits.
+    validations:
+      required: true
+  - type: textarea
+    id: summary
+    attributes:
+      label: Summary lines
+      description: The line of aps5-summary.jsonl for each capture. It holds the commit, the APS5_* switches, GPU, driver, OS, resolution and frame times.
+      render: json
+    validations:
+      required: true
+  - type: textarea
+    id: trace
+    attributes:
+      label: Traces
+      description: Attach each aps5-trace-<commit>-<pid>.json.gz (drag it into this field). They open in ui.perfetto.dev.
+    validations:
+      required: true
+  - type: textarea
+    id: digest
+    attributes:
+      label: Digest
+      description: The output of `python3 tools/trace_digest.py <trace>` (with `--stacks <file>.collapsed.txt` if you sampled the worker).
+  - type: textarea
+    id: stacks
+    attributes:
+      label: Worker stacks
+      description: Optional. The collapsed-stack file of APS5_SAMPLE_WORKER (<file stem>.collapsed.txt), attached. It opens in speedscope.app.
+  - type: checkboxes
+    id: protocol
+    attributes:
+      label: Capture
+      options:
+        - label: The caches were warm (the scene ran once and the title was restarted)
+          required: true
+        - label: No other APS5_TRACE_* or APS5_PROFILE_* switch was set and the log was not redirected
+          required: true
+        - label: Captures compared here come from the same machine, scene and settings

.github/pull_request_template.md

@@ -1,7 +1,7 @@
 ### What
 
 ### Tested
-<!-- OS, title or homebrew, what was checked. "Not tested" is a valid answer. -->
+<!-- OS, title or homebrew, what was checked. "Not tested" is a valid answer. A performance change: the summary lines of main and of this PR from the same machine and scene, with the traces attached, captured as the Performance report issue form describes. -->
 
 ### Checklist
 <!-- Rules behind each item: https://github.com/boykopovar/AnyPS5/blob/main/CONTRIBUTING.md -->

CONTRIBUTING.md

@@ -58,6 +58,7 @@ The [pull request template](.github/pull_request_template.md) is the checklist f
 - Fixes a title needs go to `main` as pull requests. A Game bring-up discussion lists the open pull requests and local changes the title still needs; update the list when one is merged, closed or replaced.
 - The PR overlap comment lists open pull requests that change the same lines or exports; agree with their authors which one goes first and declare it with `Depends on`.
 - Run the tests before opening the pull request and describe what was tested (OS, title or homebrew).
+- A pull request that claims a change in speed shows the summary lines of `main` and of the change, from the same machine and scene, and attaches the traces, captured as the [Performance report](.github/ISSUE_TEMPLATE/performance.yml) issue form describes. A slow scene is reported with the same form.
 - Investigation notes, reports, screenshots and logs go in the pull request, not in the repository. Images for documentation go in the [gist](https://gist.github.com/boykopovar/0e53f2e1426f29ecd41e3b51540b8a90) comments.
 - Say whether the change was written with AI assistance. The author of the pull request is responsible for every line of it.