fix: use local ev_values and wrap dict.values() in list()

[hashwnath]

Summary

• self.ev_values[i][0] on line 3106 references a nonexistent instance attribute, causing AttributeError at runtime when eigenvalue monitoring fires. The local variable ev_values (defined on line 3102) is the intended target.
• dict.values() returns a dict_values view in Python 3 which is not subscriptable. Wrapping in list() makes it indexable.

Test plan

• Verified self.ev_values has no definition or assignment anywhere in engine.py
• Confirmed ev_values (local) is the correct variable from line 3102
• Confirmed list() wrapping is needed for Python 3 dict_values subscriptability

Fixes #7983

[hashwnath]

Hey, I looked into this and the fix is straightforward. Two things going on here:

1. Line 3106 uses self.ev_values[i][0] but there's no self.ev_values defined anywhere on the class. The local variable ev_values from line 3102 is what was intended.
2. Even after fixing the variable name, dict.values() returns a view object in Python 3 that doesn't support indexing by position. Wrapping it in list() makes it subscriptable.