chore: (dependabot): move back to npm

[GalvinPython]

Dependabot has issues with bun, so this is moving back to npm. Also

• Removes me as assignee (codeowners)
• Updates bun.lock using actions (yay thats back again)
• Removes labels so that it doesn't break for when I restructure the repo

[Copilot]

Pull Request Overview

Move Dependabot configuration back to npm and add an automated bun.lock update workflow, while removing assignees and labels.

• Switch Dependabot package-ecosystem from bun to npm for both root and /web
• Add a new GitHub Actions workflow to keep bun.lock up to date
• Remove custom assignees and labels in dependabot.yml

Reviewed Changes

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

File	Description
.github/workflows/dependabot_bun.yml	New workflow to install with Bun and commit bun.lock
.github/dependabot.yml	Change Dependabot ecosystem to npm and drop assignees/labels

Comments suppressed due to low confidence (2)

.github/workflows/dependabot_bun.yml:20

• To ensure git pull --rebase works correctly, configure the checkout step with fetch-depth: 0 (e.g., with: fetch-depth: 0).

        uses: actions/checkout@v4

.github/dependabot.yml:2

• [nitpick] Consider rephrasing or removing informal comments/emojis to maintain a professional tone in configuration files.

# because wow dependabot is so broken for it 😭

[GalvinPython]

well done me, you just added 3 commits for no reason 👏