[Kinflou]

Summary

• Three independent "boolean" surfaces disagreed: .ids settings values required capitalized True/False, .idp package config required lowercase true/false, and .ids annotation/expression values (@deprecated = true, validator keyword args, field defaults) had no dedicated bool type at all — just an unconstrained Identifier, guessed at downstream by inconsistent string comparisons.
• BoolLiteral's leaf text is now "true"/"false" (still two literal leaves, not a combined regex — that's what keeps it unambiguous with Identifier).
• Expression gained a Bool(BoolLiteral) variant, reusing the exact same type as SettingValue::Bool, so a boolean is spelled and typed identically in settings blocks and in annotation/expression values.
• .idp's own BooleanLiteral converted from a single combined-regex leaf to the same two-literal-leaf shape — it had a live, only defensively-patched ambiguity with Identifier in freezing.rs (matched both Value::Boolean and Value::Identifier for "true"/"false" because nobody was sure which one the parser actually produced); now that it's unambiguous, the defensive Identifier arms are gone.
• value_category's dual-case leniency (accepting both true/false and True/False) is dropped — only lowercase can occur from a conforming parse now.
• This is a breaking change to .ids syntax: any schema with True/False in a settings {} block now needs lowercase.

Test plan

• cargo test clean (341 + 188 + others, 0 failed)
• cargo clippy --all-targets clean (no new warnings)
• Verified end-to-end against the real comline CLI (via a temporary local [patch], reverted after): capitalized True in a .allowed setting now fails with an accurate settings::malformed-value error ("a settings '.allowed' key only accepts 'true' or 'false'" — previously that message was wrong for .ids); lowercase true passes cleanly; @deprecated = true still warns as a bare marker (confirmed it now parses through Expression::Bool, not Identifier)