[ty] Make playground header say ty and add docs href (#24759)
## Summary
Fixes astral-sh/ty#2672
Also includes adding the href to the ty docs to the logo.
New look:
<img width="186" height="121" alt="image"
src="https://github.com/user-attachments/assets/a24a08dc-bced-4fad-87c0-d0a614d7d4b0"
/>
Done by hand in an [SVG
editor](https://yqnn.github.io/svg-path-editor/#P=M_64_10_H_37_V_0_H_5_V_10_H_0_V_35_H_5_V_54_C_5_59_10_64_16_64_H_64_V_40_H_37_V_35_H_54_C_59_35_64_30_64_24_V_10_Z_M_99_10_H_104_V_0_H_133_V_54_C_133_59_128_64_122_64_h_-53_V_40_H_101_V_35_H_79_C_74_35_69_30_69_24_V_0_H_99_Z),
so I'm not very confident in how the y looks. If anyone else knows the
process/font for how the other logos were made I would be happy to
change it.
## Test Plan
N/A playground change. Was tested locally by editing the HTML on the
playground page to match the new changes.
---------
Co-authored-by: Micha Reiser <micha@reiser.io>
