[ty] Infer dict(**TypedDict) in TypedDict context

[charliermarsh]

Summary

Given, e.g., def f() -> TD: return dict(**src), we now infer dict(**src) as matching TD if src is TD, for example. So the following are accepted, whereas on main they all produce diagnostics:

from typing import TypedDict

class TD(TypedDict):
    x: int
    y: str

src = {
    "x": 1,
    "y": "foo",
}

x: TD = dict(**src)

def f() -> TD: return dict(**src)

[astral-sh-bot]

Typing conformance results

No changes detected ✅

Current numbers

The percentage of diagnostics emitted that were expected errors held steady at 87.94%. The percentage of expected errors that received a diagnostic held steady at 83.36%. The number of fully passing files held steady at 79/133.

[astral-sh-bot]

Memory usage report

Memory usage unchanged ✅

[astral-sh-bot]

ecosystem-analyzer results

No diagnostic changes detected ✅

Full report with detailed diff (timing results)

[codspeed-hq]

Merging this PR will not alter performance

✅ 47 untouched benchmarks
⏩ 60 skipped benchmarks¹

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_{Comparing charlie/unpack-dict (f1cbea9) with charlie/unpack-literal (10f4c9a)}

Footnotes

1. 60 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. ↩