Reduce performance engineering guide word limit from 500 to 200 (#162)

* Initial plan

* Reduce perf improver sub-guide word limit from 500 to 200 words

Co-authored-by: dsyme <7204669+dsyme@users.noreply.github.com>

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Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: dsyme <7204669+dsyme@users.noreply.github.com>

Author: Copilot

workflows/daily-perf-improver.md

@@ -119,7 +119,7 @@ To decide which phase to perform:
 
 3. Create `.github/actions/daily-perf-improver/build-steps/action.yml` with validated build steps. Each step must log output to `build-steps.log` in repo root. Cross-check against existing CI/devcontainer configs.
 
-4. Create 1-5 performance engineering guides in `.github/copilot/instructions/` covering relevant areas (e.g., frontend performance, backend optimization, build performance, infrastructure scaling). Each guide should be maximum 500 words and should succinctly document practical, non-obvious, repo-specific details regarding:
+4. Create 1-5 performance engineering guides in `.github/copilot/instructions/` covering relevant areas (e.g., frontend performance, backend optimization, build performance, infrastructure scaling). Each guide should be maximum 200 words and should succinctly document practical, non-obvious, repo-specific details regarding:
   - Performance measurement strategies and tooling
   - Common bottlenecks and optimization techniques
   - Success metrics and testing approaches