feat(svg): partial connection indicator

[peterbaumert]

Summary

Closes #61

Adds a visual distinction in the SVG renderer between fully connected and partially connected ports (i.e. a cable is attached but the path does not resolve to a far-end device — e.g. switch → patch panel → open outlet).

Changes

New connection states (SVG only)

State	Fill colour	Overlay
Full connection	Green #198754	—
Partial connection (new)	Yellow #ffc107	Small warning dot (top-right corner)
Enabled, unconnected	Grey #6c757d	—
Disabled	Red #dc3545	—

How it works

• Detection: uses NetBox's existing link_peers and connected_endpoints attributes — no new ORM queries. A port is partially connected when link_peers.length > 0 AND connected_endpoints.length == 0.
• Partial fill (bg-warning): applied in status-colour mode (cable_colors off), shows yellow.
• Warning dot: a small <circle> element is injected by JS into the top-right corner of the port <rect>. It is always visible — even when cable colour mode overrides the fill — so the partial state is never hidden.

Files changed

File	Change
templates/…/deviceview.html	Added partiallyConnected to portData; updated applyPortStatus() with new branch + dot injection
templates/…/ports.html	Same as above (device-tab template)
static/…/css/device_view_svg.css	Added .dv-port.bg-warning fill rule and .dv-partial-dot style

Notes

• SVG-only feature as agreed in the issue thread — the CSS Grid path is unchanged.
• No Python/model changes required; all connection-state data is already available in the template context via NetBox's ORM.