impl Completions: Import suggestions for explicit re-exports. #2207

[asukaminato0721]

Summary

Fixes part of #2207

Added explicit re-export detection on exports and used it to surface explicit re-export paths in autoimport/quickfix searches.

Test Plan

Added an autoimport test covering explicit re-export suggestions.

[github-actions]

According to mypy_primer, this change doesn't affect type check results on a corpus of open source code. ✅

[Copilot]

Pull request overview

Improves Pyrefly’s auto-import completion results so that when a symbol is explicitly re-exported (e.g. from source import Thing as Thing), completions can suggest importing from the re-exporting “public” module rather than only from the canonical/original module. This supports the IDE feature tracker item “Completions: Import suggestions for explicit re-exports” (#2207).

Changes:

• Add export-metadata plumbing so export searches can detect whether a name is an explicit re-export.
• Include explicit re-export module paths in search_exports_exact/search_exports_fuzzy results (for user-owned modules).
• Add an LSP completion test covering the explicit re-export auto-import suggestion.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
pyrefly/lib/test/lsp/completion.rs	Adds regression test asserting auto-import prefers the explicit re-export path in completion results.
pyrefly/lib/state/state.rs	Extends search_exports callback signature to provide Exports metadata alongside computed export maps.
pyrefly/lib/state/lsp.rs	Uses explicit re-export detection to include re-export handles in export search results for auto-import completions.
pyrefly/lib/export/exports.rs	Adds Exports::is_explicit_reexport to identify ImportAsEq-style definitions.

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[meta-codesync]

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