Add splashboard, gitlogue, and gittype

[unhappychoice]

Adds three open-source Rust CLI tools, each placed alphabetically in the most relevant category:

• splashboard (Customization) - A customizable splash screen shown on shell startup and directory change, with per-directory dashboards. 97+ stars.
• gitlogue (For Developers) - A cinematic Git commit history replay for the terminal. 4700+ stars.
• gittype (Games) - A code-typing game that turns your source code into typing challenges. 1000+ stars.

All three clear the 50-star notability bar. Self-submission (I'm the author).