Implement F# types, members, overloads, and constraint solving

Parent: #8
Blocked by: #32

Outcome

Extend the semantic checker across F# nominal types, object members, interoperability, overload resolution, and generic constraints.

Acceptance criteria

• Records, unions, classes, structs, interfaces, delegates, enums, exceptions, abbreviations, inheritance, and object expressions have compiler-owned typed representations.
• Constructors, methods, properties, events, extension members, named and optional arguments, conversions, and overload ranking use stable candidate selection.
• Generic, subtype, equality, comparison, nullness, byref, statically resolved type-parameter, inline member, and unit-of-measure constraints are solved without hard-coded type or member names.
• Satisfied, unsatisfied, inaccessible, and ambiguous cases have focused positive and negative conformance programs.
• Trait and inline calls lower from resolved semantic evidence; placeholder exception stubs do not count as implementation.
• Type-provider inputs remain explicitly unsupported until the separate Provider Broker gate from #13 is implemented.

Decision inputs

Issues #5 and #13; ADRs 0014, 0015, and 0025.

This issue inherits the corpus-neutral acceptance policy in #8.

Start with parent issue #8 and blocker #32, then read decision inputs #5 and #13 and ADRs 0014, 0015, and 0025. The semantic checker must cover the listed F# representations, members, overloads, constraints, and focused conformance cases, while keeping type-provider inputs unsupported until the Provider Broker gate is implemented.