feat: add devprune icon

[VKrishna04]

Description

Adds a file icon for dev-prune, a lockfile-verified workspace cleaner CLI, matching its two per-repository config file names:

• .devprune.json — per-repository configuration (JSON schema, SchemaStore submission)
• ignore.devprune.json — opt-out marker file

The icon is the tool's leaf logo as a single vectorized path (no base64), with the brand gradient mapped to the Material palette: #00E676 (green A400) → #00E5FF (cyan A400). npm run check-colors passes, the viewBox is 0 0 16 16 with spacing around the motive, and the silhouette stays recognizable at 16 px.

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[github-actions]

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[Copilot]

Pull request overview

Adds a new file icon for the dev-prune tool’s repository config/marker files, integrating it into the theme’s file-icon mapping and icon asset set.

Changes:

• Register a new devprune file icon mapping for .devprune.json and ignore.devprune.json.
• Add the icons/devprune.svg asset used by the generated icon manifest.

Reviewed changes

Copilot reviewed 1 out of 2 changed files in this pull request and generated no comments.

File	Description
src/core/icons/fileIcons.ts	Adds filename associations to map dev-prune config/marker files to the new devprune icon.
icons/devprune.svg	Introduces the new SVG icon asset (gradient-filled leaf) for use by the icon theme.

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[PKief]

The icon looks nice, but your project is not widely adopted (first commit 1 week ago, 3 stars on github). We don't want to include icons which are purely visible and relevant for only a handful of users. Even if the icon might be nice, it's just "bloat" for our extension (without meaning that in a negative way). You can keep this PR open, but we would require to see a little more broad adoption of your project so that it makes sense to include it into our library.

I know this might not be the answer you might have expected, but I hope you can understand that. Maybe we need to make this more clear in our contributions guidelines. Anyways, I wish that you have lots of success with your project and keep going! It's really good to push something forward. And we can see, once it gets more popular and widely adopted we can also inlcude the icon into our project.