Multi-floor support, better wall physics, and PDF reports just shipped

Big update just went live. Here's what's new:

Multi-floor planning - You can now add unlimited floors, each with its own floorplan and walls. Signal from APs on other floors bleeds through realistically based on the slab material (wood frame, concrete, reinforced concrete, steel deck). The channel solver sees across floors too, so it won't put two APs on the same channel if they're directly above each other through a wood floor.

Wall attenuation got a lot more accurate - Walls are now thickness-aware. A thick concrete wall blocks more signal than a thin drywall partition, which is how it works in the real world. The heatmap no longer has any artificial cutoff radius - signal just fades naturally based on the path loss model. If you draw a metal enclosure around an AP, the solver knows those two APs don't interfere.

The solver always assigns channels now - Previously if you had more APs than available non-DFS channels (9 on 5 GHz), some APs would show as "pending" with no channel. Now it picks the least-conflicting option instead of giving up. You can see co-channel interference in the AP editor with actual signal percentages.

PDF export is actually useful - Generates a proper site survey report with a cover page, one layout page per floor, AP schedule grouped by floor, per-floor coverage scores, and a building-wide weighted average. Something you could hand to a client.

Bunch of UX stuff - Undo works for everything now (floor operations, AP property changes, wall drawing, destructive actions). Confirmation dialogs before deleting floors/APs. Keyboard navigation in all dropdowns. Walls render over the heatmap so you can actually see them.

Try it at https://deconflict.pages.dev