Rackpad 1.8.4-beta.3

This local beta candidate completes the active Rack Studio and Rack Cabling
follow-ups without changing the server API, schema, migrations, stored
inventory format or release channel. It is not published by this preparation.

Changes

• Hardware templates can add every supported appearance primitive: panel,
  handle, vent, bay, display, outlet, screw, indicator and label. Appearance
  primitives and module positions can be moved in the preview while numeric
  controls remain available for precise changes. A module position is the
  mounted area; a module is the component installed in that position.
• Port-block width and height changes regenerate the port layout rather than
  acting as position-only edits. Existing port identities remain stable.
• The classic Racks/Rooms elevation uses normalized 12-column placement with
  legacy full, left and right slots as a fallback. Full-, half- and
  quarter-width equipment can share a U on either face without overlap.
• A selected loose device defaults to a rack-top placement against the focused
  rack, preserving the existing collision validation and without reserving a
  direct rack U.
• Rack Cabling persists loose-equipment expansion separately for each room and
  migrates the existing single expansion preference. Panning and zooming retain
  the active cable, port or label selection.
• Cross-room handoff labels use the outward boundary of the originating room
  while keeping deterministic packing, collision avoidance, leaders and bounds
  protection. Rack selection uses one focused-rack handler across room-canvas,
  endpoint and placement paths.
• Rack Cabling now arranges selected rooms automatically, around a selectable
  hub, or through drag-and-keyboard manual placement. Layout preferences are
  isolated to the active browser and lab; all room, anchor, cable and label
  geometry stays in the same rendered scene.

Acceptance requested

• #164: add and duplicate each appearance primitive, drag an appearance
  primitive and module position, then resize and reposition a port block.
• #165 / #166: expand loose equipment in different rooms independently,
  pan and zoom with a cable or port selected, inspect cross-room labels at each
  originating-room boundary, and verify Auto, Hub & spoke and Manual room
  layouts after a refresh.
• #167: place full-, half- and quarter-width equipment at one U in classic
  Racks/Rooms on both faces, then place loose equipment on a focused rack top.
• #169: select every rack from the room canvas and verify that the lower
  focused-rack elevation changes each time.

Data and rollback

Schema remains 52. No migration, server API, environment-variable,
dependency or deployment contract changed. Keep a backup before any later
published upgrade. Roll back to the matching prior application state; do not
attach an older application to unsupported database schema.

Validation

The candidate includes client type checks and focused Rack Studio/Rack Cabling
tests for placement columns, port-block geometry, per-room expansion and
handoff-label lanes. The repository's standard gate must still succeed before
any later tag or publication.