fix(lint/useExhaustiveSwitchCases): improve type narrowing for default parameters

[nmhen]

Fix incorrect type inference where destructured parameters with default values were still considered to include undefined in their type union.

Fixes #7525

Summary

The useExhaustiveSwitchCases rule was incorrectly flagging switch statements as non-exhaustive when using destructured parameters with default values.

Problem: When a parameter has a default value like { b = "thing" }: { b?: "thing" | "other" | "more" }, the
variable b can never be undefined because it has a default value. However, the rule was still requiring an
undefined case in switch statements.

Solution: Added logic to detect when a discriminant variable comes from a destructured parameter with a default
value, and exclude undefined from exhaustiveness checking in those cases.

Test Plan

• Added new test case invalidIssue7525.ts with scenario of destructured parameters with defaults
  • All existing tests continue to pass
  • The new test verifies that switch statements with destructured params + defaults no longer incorrectly require
    undefined cases

Docs

No documentation changes needed - this is a bug fix that improves existing rule behavior.

[changeset-bot]

🦋 Changeset detected

Latest commit: 42d8ed3

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 13 packages

Name	Type
@biomejs/biome	Patch
@biomejs/cli-win32-x64	Patch
@biomejs/cli-win32-arm64	Patch
@biomejs/cli-darwin-x64	Patch
@biomejs/cli-darwin-arm64	Patch
@biomejs/cli-linux-x64	Patch
@biomejs/cli-linux-arm64	Patch
@biomejs/cli-linux-x64-musl	Patch
@biomejs/cli-linux-arm64-musl	Patch
@biomejs/wasm-web	Patch
@biomejs/wasm-bundler	Patch
@biomejs/wasm-nodejs	Patch
@biomejs/backend-jsonrpc	Patch

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[codspeed-hq]

CodSpeed Performance Report

Merging #7545 will not alter performance

_{Comparing nmhen:fix-exhaustive-switch-default-params (42d8ed3) with main (8a4f4fc)}

Summary

✅ 133 untouched

[siketyan]

The useExhaustiveSwitchCases uses our type inference, and the issue is not coming from the rule itself, but from the type inference. Fixing the issue within the rule is more like symptomatic therapy, and the issue still exists when the type inference is used in other rules. Implmenting the type narrowing in our type inference will help not only this rule but also other type-powered rules.