[TS Calls] Execute semantic models written in TypeScript

[CaelmBleidd]

Part of #360. Depends on #365 and P0 gate #383.

Goal

Run semantic models written as ordinary TypeScript through the normal EtsIR interpreter.

Scope

• Implement a source-model object using the same ID/target/execution contract as [TS Calls] Register and execute guarded semantic models #365. Do not add a separate backend registry, registration wrappers or duplicated implementation-kind tags.
• Load the selected model sources through the native JacoDB frontend and add their EtsIR methods to the scene.
• Bind the original receiver and arguments to the model entry point; use normal call execution for return values, exceptions, heap changes and aliases.
• Check the supported domain before entry. Unsupported states retain the configured residual fallback.
• Route nested unknown calls through the same dispatcher and prevent recursive model redirection.
• Implement Array.pop as source code using indexing and length, not by calling pop again. Correct array-length writes must use the engine's actual array-length representation.
• Keep the initial supported receiver/element domain explicit; unsupported/unknown/fake representations fall back. A single possible type returned from a multi-valued stream is not proof.
• Reuse existing frontend loading, scene validation and signature resolution. Cache/loading work should be driven by actual reuse, not a new generic artifact subsystem.
• Record source/artifact content identity where externally loaded models can differ independently of the tool revision. Do not introduce manually managed model versions or compatibility negotiation.

Definition of Done

• One pure source model and the stateful Array.pop case run end to end.
• Focused tests compare supported source-model behavior with original TypeScript for normal results, exceptions, mutation, aliases and residual inputs.
• Model redirection cannot recursively re-enter the same unsupported call forever.
• Array length, return values and input reconstruction remain consistent.
• [TS Calls][P0] Finish simplifying the model contract before further integration #383's simplified configuration and documentation are shared with PR [TS Calls] Add guarded semantic models with a simplified contract #377.
• Existing PR [TS Calls] Execute semantic models written in TypeScript #380 is adapted and verified; no duplicate implementation is required.

A model backend platform, complete ECMAScript array semantics and unrelated core redesign are outside this issue. Extend domains only with a demonstrated case and tests.