[TS] Model Array and String operations through EtsIR

[CaelmBleidd]

String algorithms execute through ordinary EtsIR length, indexing, comparisons, loops and concatenation. UTF-16 reads support bounded symbolic strings and positions, with undefined for invalid or out-of-range indexes. The private length/range-copy intrinsics and unused initial-state callbacks are removed.

Private UTF-16 helper dispatch now checks the exact bundled artifact and class owner, preserving foreign same-named declarations. String and Array builtins ignore semantically unused extra arguments after ordinary source argument evaluation, including Array.pop.

Validation: the earlier published head passed the full local usvm-ts suite (1,190 passed, 142 skipped). The current cleanup passed 62 focused model/source/SDK regressions and detektMain/detektTest. Fresh CI for the current head is the broader gate.

Review focus: artifact identity, meaningful argument slots, canonical string indexes, backing bounds, symbolic search/slicing and sparse-array fallback. ASCII case conversion retains its bounded non-ASCII residual fallback. String-index writes remain outside this published change.

Based on main eb632e9 after #446. Preserve Array.isArray registration alongside the Array/String sequence models. All ten own commits are retained; the conflict changes only catalog expectations. Validation on bfa7cb8: 77 catalog, Array.isArray, sequence and fresh-string tests passed without skips; Detekt main/test passed. Full CI run 38381980353 is running on this exact head.

[CaelmBleidd]

@copilot resolve the merge conflicts in this pull request

[Copilot]

@copilot resolve the merge conflicts in this pull request

Resolved. I addressed the merge conflict in commit 8c95ba9 by restructuring the overlapping built-in model catalog assertions so the branch now merges cleanly with main without introducing a merge commit.