fix: resolve relative profile generation links

[ShiroKSH]

Summary

• resolve active profiles whose generation link is relative to the profile directory
• report a symlink loop instead of recursing indefinitely
• cover both paths with focused unit tests

Checks

• cargo fmt --check
• git diff --check

Fixes #516.

[ShiroKSH]

@Mergifyio queue

[mergify]

queue

☑️ Command disallowed due to command restrictions in the Mergify configuration.

Details

• sender-permission >= write