fix(compiler): repair generic dictionary dispatch for pointer-constraint receivers - #161

Interface-constraint generic methods lowered a property-keyed dispatch lambda that called the method directly on the receiver value. When Go code converts the address of a variable to the constraint's pointer type-set element (M(&msg) over an interface embedding *T), the runtime receiver arrived as a VarRef wrapper with no method properties, so the call failed at runtime with TypeError: is not a function.

Struct receivers in dictionary method lambdas are now unwrapped through the runtime pointerValue helper before the property-keyed call; class instances pass through unchanged and interface descriptors keep their existing shape.

The same chain exposed a second lowering gap: an explicit instantiation that leaves trailing type parameters to constraint inference, such as decodeLocalPairing[*pairingOffer] over [M localPairingMessage[T], T any], emitted type arguments only for the explicitly written parameter. The generic body then resolved the remaining parameter's zero value as null and dispatched on nil, surfacing downstream as index-out-of-range failures. The lowering now reads the full argument list recorded by go/types Instances when explicit arguments run out.

compilerSemanticsVersion is bumped so cached artifacts recompile with the new dispatch shape instead of serving pre-fix output on warm builds.