Rackpad 1.8.4-beta.5

This beta follows up on Rack Studio placement, managed cable routing, Rack
Cabling labels, and Visible Links text. Schema remains 52. There is no
migration, environment-variable, dependency, or deployment change.

What to check

• #170: In Studio Beta, drag a device onto another device at a different U
  and onto an occupied half-width slot. Also try editing Start U in the
  inspector. The conflict should be clear, and both devices should remain at
  their original positions after reload.
• #171: Route Smooth Managed cables through front-to-rear brush-panel guides
  and multiple guides. Front and rear paths should bend smoothly, honor each
  guide, and match SVG/PNG exports. Orthogonal Managed stays right-angled.
• #165: Select a port or cable, then pan and zoom in Rack Cabling. Its label
  should stay readable near the selected endpoint without covering equipment.
• #173: Check the port line in Diagram Visualizer's Visible Links panel;
  there should be a space on each side of “to”.
• #164: Confirm appearance creation, one-/three-/sixteen-port NIC modules,
  portless fans, and moving a module position by dragging its artwork. Broader
  template features remain separate future work.

Existing overlapping records are preserved until explicitly moved. If a beta
upgrade needs to be rolled back, use the prior matching application and backup;
this update does not change the stored schema.

The beta branch and release-tag workflows must pass their required quality,
CodeQL, and security checks before this release is considered published.