[Feature]: Add maximum capacity to storage_bins

[dmueller-dev]

Problem Statement

It's possible to put more bottles in a virtual storage bin than actually fit in the real one.

Proposed Solution / Workflow

Add a maximum capacity to the storage_bins table.
Make the field optional (NULL allowed).
Check against this maximum capacity when assigning bottles to storage bins.
Optionally show a % usage of the cellar and individual bins in the admin hub.

Alternatives Considered

No response

Additional Context

No response

Checklist

• I have searched existing issues to verify this feature has not already been requested.