Fix casting to an interface that extends another interface with methods

[ASDAlexander77]

Summary

Follow-up to #265's "known follow-up" note: an extends-based version of the multi-method interface cast scenario (interface Base {base;addBase()} interface Accumulator extends Base {total;add();addTwice();scaled()}) still failed — confirmed unrelated to cross-module/import, reproduces with a plain same-module cast.

Two separate bugs, both in the interface vtable machinery:

1. Compile-time failure — InterfaceInfo::getVirtualTable's recursion into extends didn't propagate the methodsAsFields flag to the recursive call, so an inherited method always took the METHOD resolution path instead of the FIELD path object-literal methods actually need. That path's resolver is a deliberate no-op stub (comment: "we do not return method, as it should be resolved in fields request"), so any non-conditional inherited method made the whole cast fail with a bare error: failed statement — no diagnostic text anywhere.
2. Runtime crash, after fixing (1) — the cast now compiled, but calling an inherited method (even the first one, vtable slot 0) crashed with an access violation. The runtime vtable-patch loop (mlirGenCreateInterfaceVTableForObject) only walked an interface's own directly-declared methods (InterfaceInfo::methods), never inherited ones — so an inherited method's vtable slot was never patched with a real function pointer and kept its initial offset-placeholder value, which got read and called as if it were a function pointer.

Fix

1. Pass methodsAsFields through on the extends recursive call in getVirtualTable (one line).
2. Added InterfaceInfo::getAllMethods() to flatten own + inherited methods (extends-first, matching getVirtualTable's own traversal order); the vtable-patch loop now uses this instead of the interface's own methods list alone.

Test plan

• Same-module and cross-module repros manually verified end-to-end (105/3/7/14, all four members — one inherited, three own — correct)
• New regression tests: 00object_annotated_method_extends_interface.ts (same-module, compile+jit) and export/import_object_literal_structural_typed_extends_interface.ts (cross-module, compile+jit)
• Full 744-test suite (740 existing + 4 new): 100% pass, no regressions

Known limitation (not hit by this fix, flagged for later)

Only verified for single-level extends. An inherited InterfaceMethodInfo's virtualIndex is assigned standalone by the base interface's own assignCanonicalVirtualIndexes() — for a single extends target this coincidentally lines up with the derived interface's combined vtable (base slots start at offset 0), but multi-level or diamond extends isn't verified and may need the same vtableOffset-accumulation treatment findField/findMethod already document for a related scenario.

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