docs: benchmark dashboard exploration tool

[missBerg]

What type of PR is this?
Add Benchmark Dashboard Tool and JS Tools Directory
This PR adds a standalone JavaScript benchmark dashboard tool and establishes a /tools/ directory structure for future JS utilities.

---

What this PR does / why we need it:
This helps users discover and explore the existing benchmark report results current only available in markdown for each EG release.

---

Deployment Test URL: https://envoy-gateway-preview.netlify.app/tools/benchmark-report-explorer/

What's Added

• Standalone Benchmark Dashboard: Interactive tool for visualizing EG performance data across versions at /tools/benchmark-report-explorer/
• JS Tools Directory Structure: Creates /site/tools/ as the home for standalone JavaScript utilities
• Hugo Partial Integration: New {{< benchmark-dashboard >}} shortcode for easy embedding in content pages
• Release Benchmark Integration: Provides a dedicated space to surface benchmark reports for EG releases

Technical

• Self-contained React/TypeScript tool that builds to Hugo static assets
• Uses Shadow DOM for safe integration with the main site
• Accessible at http://localhost:1313/tools/benchmark-report-explorer/
• Hugo shortcode supports configuration via parameters (version, showHeader, class, etc.)

Value

• Gives us a proper place to showcase performance data for each EG release
• Establishes a pattern for adding more web hosted tools in the future
• Helps users and contributors track performance trends over time
• Easy to embed in any Hugo content page using the shortcode
• This creates the foundation for surfacing benchmark data publicly and provides a scalable structure for additional JS-based tools.

Enhancements After This PR

• Add link to tools directly from main page
• Have the CI Benchmark Report generate output in JSON to integrate directly

---

Which issue(s) this PR fixes:
N/A

Release Notes: No

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 70.78%. Comparing base (6f42531) to head (fe5e646).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6399      +/-   ##
==========================================
- Coverage   70.80%   70.78%   -0.03%     
==========================================
  Files         220      220              
  Lines       37132    37132              
==========================================
- Hits        26291    26283       -8     
- Misses       9300     9305       +5     
- Partials     1541     1544       +3     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[zhaohuabing]

This is amazing! @missBerg

[zhaohuabing]

I think the spike in EG’s max CPU usage in 1.4.1 might be an anomaly — I haven’t seen a similar pattern in other PRs.

v1.4.1

|Test Name                                                  |Envoy Gateway CPU (%) <br> min/max/means
|-                                                          |-                                       
|scaling up httproutes to 10 with 2 routes per hostname     |0.27 / 0.67 / 0.45                      
|scaling up httproutes to 50 with 10 routes per hostname    |0.40 / 4.33 / 0.97                      
|scaling up httproutes to 100 with 20 routes per hostname   |0.40 / 8.67 / 1.36                      
|scaling up httproutes to 300 with 60 routes per hostname   |0.47 / 79.87 / 3.90                     
|scaling up httproutes to 500 with 100 routes per hostname  |0.40 / 1.20 / 0.75                      
|scaling up httproutes to 1000 with 200 routes per hostname |0.13 / 1.13 / 0.80                      
|scaling down httproutes to 500 with 100 routes per hostname|0.67 / 5.67 / 1.33                      
|scaling down httproutes to 300 with 60 routes per hostname |0.67 / 46.53 / 4.41                     
|scaling down httproutes to 100 with 20 routes per hostname |0.80 / 38.20 / 5.63                     
|scaling down httproutes to 50 with 10 routes per hostname  |0.80 / 7.53 / 1.54                      
|scaling down httproutes to 10 with 2 routes per hostname   |0.80 / 3.47 / 1.14                      

https://github.com/envoyproxy/gateway/actions/runs/15848691881/job/44682066547?pr=6397

|Test Name                                                  |Envoy Gateway CPU (%) <br> min/max/means
|-                                                          |-                                       
|scaling up httproutes to 10 with 2 routes per hostname     |0.20 / 0.87 / 0.49                      
|scaling up httproutes to 50 with 10 routes per hostname    |0.40 / 3.53 / 1.06                      
|scaling up httproutes to 100 with 20 routes per hostname   |0.47 / 6.13 / 1.14                      
|scaling up httproutes to 300 with 60 routes per hostname   |0.47 / 14.46 / 2.44                     
|scaling up httproutes to 500 with 100 routes per hostname  |0.47 / 18.27 / 2.48                     
|scaling up httproutes to 1000 with 200 routes per hostname |0.60 / 39.60 / 4.62                     
|scaling down httproutes to 500 with 100 routes per hostname|0.60 / 30.80 / 3.71                     
|scaling down httproutes to 300 with 60 routes per hostname |0.60 / 14.40 / 2.14                     
|scaling down httproutes to 100 with 20 routes per hostname |0.60 / 13.73 / 2.10                     
|scaling down httproutes to 50 with 10 routes per hostname  |0.60 / 5.00 / 1.34                      
|scaling down httproutes to 10 with 2 routes per hostname   |0.60 / 3.47 / 1.07                      

https://github.com/envoyproxy/gateway/actions/runs/15834934850/job/44637109719?pr=6390

|Test Name                                                  |Envoy Gateway CPU (%) <br> min/max/means
|-                                                          |-                                       
|scaling up httproutes to 10 with 2 routes per hostname     |0.13 / 0.67 / 0.47                      
|scaling up httproutes to 50 with 10 routes per hostname    |0.27 / 3.80 / 0.92                      
|scaling up httproutes to 100 with 20 routes per hostname   |0.33 / 4.93 / 1.00                      
|scaling up httproutes to 300 with 60 routes per hostname   |0.47 / 18.13 / 2.34                     
|scaling up httproutes to 500 with 100 routes per hostname  |0.47 / 14.87 / 2.41                     
|scaling up httproutes to 1000 with 200 routes per hostname |0.53 / 34.53 / 3.80                     
|scaling down httproutes to 500 with 100 routes per hostname|0.53 / 27.27 / 3.35                     
|scaling down httproutes to 300 with 60 routes per hostname |0.60 / 13.87 / 2.09                     
|scaling down httproutes to 100 with 20 routes per hostname |0.60 / 10.47 / 1.80                     
|scaling down httproutes to 50 with 10 routes per hostname  |0.60 / 4.20 / 1.20                      
|scaling down httproutes to 10 with 2 routes per hostname   |0.60 / 2.93 / 1.02        

[zirain]

/retest

[cnvergence]

Awesome 🎉