Add feebas fishing tiles for gen iv

[Machine-Maker]

Change description

Added feebas fishing encounter for Gen IV (just in D/P and Platinum)

AI coding assistance disclosure

Again, just Claude to help me understand encounter slots.

Contributor check list

• I have written a description of the contribution and explained its motivation.
• I have written tests for my code changes (if applicable).
• I have read and understood the AI Assisted Contribution guidelines.
• I will own this change in production, and I am prepared to fix any bugs caused by my code change.