[P0] Ground CoC scaffolding in the exact target signature and extensibility rules

[jackyclever]

CLI/Core scope

Ensure generated CoC scaffolding matches the canonical target method and refuses generation when eligibility or signature facts are incomplete.

Migrated from Aether #6.

Current problem

A generic public void method() { next method(); } scaffold cannot safely represent parameters, return values, defaults, modifiers, target kind, or extensibility restrictions.

Acceptance criteria

• Resolve one canonical target object and exact declaring method.
• Use structured method facts for target kind, visibility/modifiers, static state, return type, ordered parameters, attributes, and inheritance.
• Produce separate baseSignature, wrapperSignature, and nextCall facts.
• Remove default parameter values only from the wrapper signature.
• Preserve return behavior and all arguments.
• Evaluate Wrappable, Hookable, Replaceable, final, visibility, and platform restrictions.
• Refuse generation on missing index, ambiguity, parse diagnostics, or unsupported syntax.
• Add golden cases for class/table/form targets, parameters, returns, defaults, attributes, inheritance, and existing extensions.
• Keep automatic writes to company models disabled; tests write only to disposable locations/models.