Fix flow-sensitive narrowing after raise, make ComplexType#exclude conformance-based

[apiology]

This PR was written by Claude Code on behalf of @apiology.

raise 'no' if x.is_a?(Array) never narrows x's type for the rest of the method, because raise is not its own AST node type — the parser gem represents it as a plain method call (:send), unlike return/next/redo/retry which are real node types. FlowSensitiveTyping#always_leaves_compound_statement? checked for a :raise node type that can never occur, so the narrowing fact was silently never attached.

# @param x [Symbol, Array<Symbol, Array>]
# @return [Symbol, String]
def self.as_simple_pred(x)
  raise 'no' if x.is_a?(Array)
  x
end

typecheck --level strong reported: Declared return type ::Symbol, ::String does not match inferred type ::Symbol, ::Array<::Symbol, ::Array>.

Fixed by recognizing a bare, receiver-less raise call by name in always_leaves_compound_statement?.

Separately, once narrowing does produce an exclude type, ComplexType#exclude and UniqueType#exclude used plain array subtraction (items - exclude_types.items), matching only by ==/hash. That never matches a parameterized member (Array<Symbol, Array>) against the plain type being excluded (Array), unlike intersect_with, which already handles this via conforms_to?. Fixed #exclude to reject a member when it conforms to one of the excluded types. This is intentionally one-directional: excluding Array removes Array<Symbol, Array> (every Array<Symbol, Array> is an Array), but excluding Array<Integer> does not remove a plain, unparameterized Array member (not every Array is an Array<Integer>).

Test plan:

• New specs in spec/parser/flow_sensitive_typing_spec.rb: raise-guard excludes a parameterized member, leaves an unparameterized member alone, excludes a narrower member than the class actually tested.
• bin/solargraph typecheck --level strong on the reported repro: 0 problems.
• Full suite: 1627 examples, 0 failures.