feat(semantic): add TS1038 "declare modifier cannot be used in an already ambient context"

[camc314]

Implement TypeScript error TS1038 which reports when the declare modifier is used inside a declare namespace or declare module block.

This correctly allows declare at the top level of .d.ts files, but errors when declare is nested inside another declare block.

🤖 generated with help from Claude Opus 4.5

[camc314]

• feat(semantic): add TS1038 "declare modifier cannot be used in an already ambient context" #16755 👈 (View in Graphite)
• main

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[codspeed-hq]

CodSpeed Performance Report

Merging #16755 will not alter performance

_{Comparing c/12-11-feat_semantic_add_ts1038_declare_modifier_cannot_be_used_in_an_already_ambient_context_ (3cfecd1) with main (083e081)¹}

Summary

✅ 38 untouched
⏩ 7 skipped²

Footnotes

1. No successful run was found on main (5defeed) during the generation of this report, so 083e081 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

2. 7 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩