Testing: Corpus and “mutant” seed suite

[Cass402]

Summary

Add a formal test corpus for the analyzer including known-good programs and intentionally broken “mutant” cases.
Related to #3

Why it matters

This ensures regression safety and validates rule coverage.

Proposed Approach

•	Include:
•	Anchor example programs
•	SPL Token, Token-2022, Associated Token Account, Stable Swap
•	“Mutant” PDAs with:
•	Seed order swaps
•	Missing bumps
•	Wrong endianness
•	User-controlled seeds without guards
•	Use these as regression tests in CI.