[TS] Preserve computed property Get and Put evaluation order

[CaelmBleidd]

Generic computed property reads, calls and tags now evaluate the key expression, reject a nullish receiver, and then perform key coercion in the correct order. Computed write references retain the raw key so Get and Put each convert it at their own evaluation point; ordinary assignment evaluates and saves its RHS before Put-time coercion. An obsolete PropertyRef fallback is removed from the replaced computed-write path. The scope is key/Get/Put ordering; numeric conversion of postfix results is outside this change.

Validation on the final combined stack: typecheck/build; computed-access-order.spec.ts: 22/22 and optional-callee-wrappers.spec.ts: 29/29 within the full TypeScript suite: 477/477 across 37 files; selected Kotlin frontend JSON/model tests: 62/62; license checks and diff-check. Tests compare native JavaScript and serialized IR event traces, exceptions, stored properties and selected results. No skips or failures; CI and downstream USVM execution were not run.

The original change is preserved on the corrected parent, keeping this PR independently reviewable in its original stack position.

Validation on cae216a4d2635ab40e3b85bd9039b0b67125bcd5: Tests 59 passed (59); frontend typecheck and git diff --check passed. The final #425 tree is identical to the tree that passed all 622 frontend tests across 40 files and the frontend build. These checks validate frontend/serialized IR behavior; downstream USVM execution and GitHub CI remain separate gates.