chore: add dependabot configuration

[ProfRandom92]

Motivation

• Enable automated weekly dependency update checks for repository maintenance across GitHub Actions, Python packaging, and workspace npm apps.
• Ensure Dependabot targets the repository root for Actions and pip and the specific app folders for npm to avoid broad scope.

Description

• Add .github/dependabot.yml that schedules weekly updates for github-actions at /, pip at /, npm at /dashboard/app, and npm at /showcase/app.
• Keep the change narrowly scoped by modifying only .github/dependabot.yml and not touching code, workflows, or fixtures.

Testing

• Ran python scripts/run_checks.py and the script completed successfully; it temporarily created docs/reports/check-report.md which was restored so the final commit contains only .github/dependabot.yml.
• Confirmed the repository now contains the new file with the expected entries and no other files were committed.

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Codex Task

[gemini-code-assist]

Code Review

This pull request introduces a Dependabot configuration file to automate weekly dependency updates for GitHub Actions, pip, and npm across multiple project directories. The reviewer suggests enhancing the configuration by adding labels for better triage, specifying a 'chore:' commit message prefix to align with repository conventions, and implementing grouping to reduce pull request noise.