feat: add no-unused-props rule

[baseballyama]

close: #1028

[changeset-bot]

🦋 Changeset detected

Latest commit: cfe9251

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

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Name	Type
eslint-plugin-svelte	Minor

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[baseballyama]

mts can be ts now.

PR Overview

This PR introduces the new rule "svelte/no-unused-props" to warn developers about declared props that are not used, thereby helping identify dead code and improve component clarity.

• Adds documentation for the new rule
• Implements the rule logic in the ESLint plugin
• Updates tests, configurations, and related files to integrate the new rule

Reviewed Changes

File	Description
docs/rules/no-unused-props.md	Adds detailed documentation and examples for the new rule
packages/eslint-plugin-svelte/src/rules/no-unused-props.ts	Implements the rule logic for detecting unused props
packages/eslint-plugin-svelte/tests/**	Adds new YAML test fixtures to cover various invalid cases
packages/eslint-plugin-svelte/src/configs/flat/recommended.ts	Updates recommended configuration with the new rule
packages/eslint-plugin-svelte/src/rule-types.ts	Extends the rule types for the new rule
README.md, docs/rules.md, packages/eslint-plugin-svelte/src/utils/rules.ts	Adds references and imports for the new rule

Copilot reviewed 84 out of 84 changed files in this pull request and generated no comments.

Comments suppressed due to low confidence (1)

packages/eslint-plugin-svelte/src/rules/no-unused-props.ts:291

• [nitpick] The function name 'hasRestElement' may be misleading as it checks for a rest element by testing if the used properties set is empty. A more descriptive name (e.g., 'patternHasRestElement') could improve code readability.

function hasRestElement(usedProps: Set<string>): boolean {

[ota-meshi]

Thank you!

[Jerboas86]

This PR gives false positive with brand types and tuples in typescript

[baseballyama]

@Jerboas86 We’ve released v3.2.1. Could you please verify if this issue has been resolved? As this rule is relatively complex, there might still be some false positives.

[Jerboas86]

@baseballyama still here for both (tuples and brand types) with v3.2.1

[baseballyama]

@Jerboas86

Can you share some repl?
Like below?

  const { foo, bar }: { foo: [string, number], bar: string & v.brand("bar") } = $props();

[ota-meshi]

Hey guys.
We have an issue template for reporting bugs.
To ensure we can fix the issue, could you please use it and share the details of the bug you have with the plugin and your repository where we can reproduce the issue?

[baseballyama]

I've created a issue for above issue: #1134