Add short aliases for global enum containers

[deevus]

Parent

Parent PRD: #5

What to build

Add short top-level aliases for global enum containers so a global enum can be looked up with either its fully-qualified name or short name. For example, gdoc JoyButton should resolve to the same enum documentation as gdoc @GlobalScope.JoyButton. Alias behavior should be deterministic and should not unexpectedly overwrite unrelated non-enum symbols.

Acceptance criteria

• Global enum containers receive short top-level aliases.
• JoyButton resolves to the same user-facing enum documentation as @GlobalScope.JoyButton.
• Fully-qualified global enum lookup remains available.
• Alias generation has deterministic precedence and does not unexpectedly replace unrelated symbols.
• Cache generation/readback works for both short and fully-qualified lookup forms.
• Regression tests cover both lookup forms and alias precedence behavior.

Blocked by

• Generate fully-qualified enum container docs #6