What do these changes do

Implements exemptions from Python typing documentation's type completeness guidelines in the type hint analyzer.

What was wrong

The analyzer flagged legitimate cases that don't require type annotations per PEP 561:

• Constants with simple literals (MAX_VALUE = 100)
• Enum values
• Type aliases without explicit TypeAlias annotation
• __init__ return types
• Special module symbols (__all__, __version__, etc.)
• Special class symbols (__slots__, __dict__, etc.)

Additionally, the type alias detection was too broad, incorrectly exempting:

• Value subscripts like VALUE = mapping["key"]
• Bitwise flag operations like FLAGS = FLAG_A | FLAG_B or MASK = 1 | 2

How this fixes it

Detection methods added:

• _is_exempt_module_symbol() / _is_exempt_class_symbol() - special dunders
• _is_simple_literal() - only str/int/float/bool/None (excludes bytes, ellipsis)
• _is_constant_name() - ALL_CAPS including private (_MAX_VALUE)
• _is_in_enum_class() - base class tracking
• _looks_like_type_expr() - distinguishes type expressions from value expressions
• _is_type_alias_without_annotation() - conservative pattern matching with proper type/value distinction

Core logic updates:

• check_function_type_hints() - exempts __init__ return types
• visit_Assign() - skips all exempt variables before flagging
• visit_ClassDef() - tracks base classes for Enum detection
• _is_type_alias_without_annotation() - validates subscript bases are known types and checks both operands of | expressions to distinguish type unions (int | str) from bitwise operations (FLAG_A | FLAG_B)
• _looks_like_type_expr() - checks if expressions look like types (built-in types, typing keywords, None constant, PEP 585 types) to prevent false positives

Optimizations:

• Module-level constants (_NONE_TYPE, _TYPE_ALIAS_KEYWORDS) avoid repeated computations
• Deprecated AST nodes (ast.Num, ast.Str) replaced with ast.Constant

Code cleanup based on review:

• Removed unused _has_final_annotation() helper method
• Removed unused target parameter from _is_type_alias_without_annotation()
• Removed dead code check for None in _is_simple_literal()
• Fixed documentation to accurately reflect that constant exemption is based on ALL_CAPS naming + simple literal check only (does not consult Final annotations)
• Improved type alias detection to distinguish between:
  • Type subscripts (list[str]) vs value subscripts (mapping["key"])
  • Type unions (int | str, list[str] | None) vs bitwise operations (FLAG_A | FLAG_B, 1 | 2)

Results:

• 82 fewer false positives (387 vs 469 module variables flagged)
• All functions now 100% complete (due to __init__ exemption)
• Accurate type alias detection prevents misclassification of value subscripts and bitwise operations
• Documentation updated in README.md with accurate exemption details

Your checklist for this pull request

• Passed code styles and structures
• Passed code linting checks and unit test

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