Add more realistic bench fixtures (#95807)
This adds more fixtures modeled after Flight payloads from real sites:
- Vercel Dashboard-like (very app-y)
- React Docs-like after App Router conversion (mostly MDX site)
- Vercel Blog-like (passing down data from CMS)
(Actual data is randomly generated with a seed)
These are simplifications but I tried to incorporate the originals'
corresponding quirks. Such as Vercel Dashboard having many client
components; syntax highlight with many small spans in React Docs; Vercel
Blog currently shipping a load of data unnecessarily on the index page.
(The last one is not ideal but I think we should actually benchmark
"bad" cases like this too so I kept that.)
### Screenshots
<img width="1325" height="1021" alt="Screenshot 2026-07-15 at 04 29 43"
src="https://github.com/user-attachments/assets/62c80722-6fd5-4884-89db-106345f6412d"
/>
<img width="1360" height="994" alt="Screenshot 2026-07-15 at 04 30 21"
src="https://github.com/user-attachments/assets/0db93cd8-43ca-41df-b3e2-c422e0c94656"
/>
<img width="1368" height="991" alt="Screenshot 2026-07-15 at 04 30 43"
src="https://github.com/user-attachments/assets/9369e9be-12a4-4a1e-af32-01b6fdd4a457"
/>
### Comparison with real payloads
```
=== dashboard.html (fixture) vs p-overview.html (real)
total KB 208 637
rows (model/I/T/other) 186/48/7/1 240/125/5/27
byte share model/I/T % 92/4/4 36/62/2
median row size B 590 106
max depth 28 53
mean depth 8.4 10.5
elements per KB(model) 14.9 5.2
pure-data byte share % 24 21
client-ref elements % 41 32
objects:elements ratio 1.17 1.23
avg props per element 1.7 3.1
median children fanout 4 4
string bytes % 24 54
median string len B 10 15
row refs per KB 0.9 0.4
encoded scalars per KB 3.5 1.2
undefined markers 347 740
=== docs.html (fixture) vs nextjs-docs.html (real)
total KB 261 487
rows (model/I/T/other) 58/15/7/1 55/43/2/20
byte share model/I/T % 93/1/6 94/6/0
median row size B 193 340
max depth 27 32
mean depth 21.9 12.3
elements per KB(model) 0.8 0.8
pure-data byte share % 8 9
client-ref elements % 16 33
objects:elements ratio 6.26 4.92
avg props per element 1.7 2.8
median children fanout 4 4
string bytes % 47 64
median string len B 17 35
row refs per KB 0.2 0.1
encoded scalars per KB 7.5 2.9
undefined markers 1949 1377
=== blog.html (fixture) vs vercel-blog.html (real)
total KB 475 797
rows (model/I/T/other) 41/15/0/1 102/53/7/14
byte share model/I/T % 100/0/0 87/8/5
median row size B 426 505
max depth 34 44
mean depth 9.7 12.2
elements per KB(model) 0.8 1.1
pure-data byte share % 92 85
client-ref elements % 23 33
objects:elements ratio 28.92 16.39
avg props per element 1.9 2.7
median children fanout 3 4
string bytes % 46 48
median string len B 6 9
row refs per KB 0.1 0.1
encoded scalars per KB 0.4 0.6
undefined markers 161 426
```
---------
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
