proposal: `prefer_const_unmodified`

[FMorschel]

<lint_name>

Replace <lint_name> above with your proposed rule name. (See notes on naming in Writing Lints.)

Description

Provide a short description suitable for display in console output.

Details

Give a detailed description that should provide context and motivation. Ideally this could be used directly in the rule's documentation.

Kind

Does this enforce style advice? Guard against errors? Other?

Bad Examples

Add a few examples that demonstrate where this lint should fire.

Good Examples

Add a few examples that demonstrate a “good” adoption of this lint’s principle.

Discussion

Add any other motivation or useful context here.

Discussion checklist

• List any existing rules this proposal modifies, complements, overlaps or conflicts with.
• List any relevant issues (reported here, the SDK Tracker, or elsewhere).
• If there's any prior art (e.g., in other linters), please add references here.
• If this proposal corresponds to Effective Dart or Flutter Style Guide advice, please call it out. (If there isn't any corresponding advice, should there be?)
• If this proposal is motivated by real-world examples, please provide as many details as you can. Demonstrating potential impact is especially valuable.