fix(dynamic): map unmappable function params/returns and type parameters to JSVAL

[techfreaque]

Problem

In --dynamic mode, three categories of types could not be mapped to IR types, causing SC errors on valid programs that use heavily-generic npm packages (Drizzle, Zod, React):

1. Function params/returns with no static IR mapping (e.g. (schema: z.ZodTypeAny) => void): emitted SC2008 on the containing record type.
2. TypeParameter with no bound or an unmappable bound (e.g. TConfig extends z.AnyZodObject): fell through to null, poisoning any intersection that contained it.
3. Multi-signature function types (overloaded functions / intersection overloads from TEvents callbacks): had no static lowering path, causing SC1090.

Fix

types.ts:

• Function param: if pt is null in --dynamic mode, use JSVAL. The param accepts any island value.
• Function return: if ret is null in --dynamic mode, return funcOf(params, JSVAL). The function is callable; the return value rides the island.
• TypeParameter fallback: call checker.getBaseConstraintOfType(widened) and recursively map the constraint. If the constraint maps (e.g. TSchema extends z.ZodTypeAny → JSVAL), the parameter maps to the same type.
• Multi-signature → JSVAL with stdlib carve-out: callSigs.length > 1 in --dynamic returns JSVAL, except when every declaration comes from a stdlib file (@types/node etc.) — those have static overload-selection lowerings that must not regress (e.g. spawnSync, readFileSync).

ts7/checker.ts: adds getBaseConstraintOfType method to CheckerFacade.

lowering/lowerer.ts: exports esOwnKeyOrder for downstream use.

Verification

A program that imports Drizzle ORM with 30+ table joins, Zod schemas with TSchema extends z.ZodTypeAny, and overloaded event callback types compiles without SC errors. spawnSync, readFileSync, and other stdlib overloads retain their static lowerings. packages/compiler builds clean.

Non-goals

MIDI type support (node-midi / @julusian/midi) is intentionally excluded from this PR — it belongs in a separate focused change.

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