[Feature]: Show storage quota usage and handle quota-exceeded in the Cloud UI

[DenizAltunkapan]

Problem

The Cloud Page backend validates a per-user storage quota before accepting an upload, but the Vault Web frontend does not show the user anything about their quota. Users cannot see how much space they have used or have left, and when an upload is rejected for exceeding the quota there is no clear, dedicated feedback.

Example scenario:

• A user has nearly filled their storage quota.
• They try to upload a large file and the backend rejects it because the quota would be exceeded.
• Today the user sees no usage information beforehand and only a generic failure afterwards, with no indication that the quota was the cause.

Proposed solution

Surface storage quota usage in the Cloud UI and handle the quota-exceeded response explicitly.

Scope:

• Show the current storage usage and total quota somewhere visible in the Cloud view, for example a usage bar with used and total space.
• Update the displayed usage after uploads and deletions so it stays accurate.
• Detect the backend quota-exceeded response on upload and show a clear, specific message telling the user they are out of space, using the existing toast notifications rather than a generic error.
• Keep the usage indicator readable on small screens.

Dependencies:

• The backend storage quota validation already exists and was added in feat: add per-user storage quota validation before file uploadFeature/per user storage quota cloud-page#65. If a dedicated usage endpoint is needed to read current usage and the quota limit, that should be confirmed against the backend and tracked separately if missing.

Acceptance criteria

• The Cloud UI shows the user's current storage usage and total quota.
• The displayed usage updates after uploads and deletions.
• An upload rejected for exceeding the quota shows a clear, specific message via toast notifications.
• The usage indicator is readable on desktop and mobile widths.

Related: consumes the backend storage quota validation from Vault-Web/cloud-page#65.

[priyanshuvishwakarma273403]

@DenizAltunkapan can work on this issue??

[DenizAltunkapan]

@priyanshuvishwakarma273403 i assigned you