refactor: change negated field syntax from !field to -field

[zharinov]

Summary

Change negated field syntax from !field to -field for consistency with tree-sitter query syntax.

Before: (node !field_name)
After: (node -field_name)

Rationale

The - prefix is more consistent with tree-sitter's negation conventions and avoids confusion with the ! operator in other contexts.

Changes

• parser/cst.rs - Add Minus token
• parser/grammar/fields.rs - Parse -field syntax, deprecation warning for !field
• parser/grammar/expressions.rs - Handle both tokens
• diagnostics/message.rs - Add deprecation warning
• Updated tests and snapshots

Migration

Old !field syntax still works but emits a deprecation warning.

Test plan

• All 705 tests pass
• Clippy passes