feat(desktop,doctor): scan-to-open QR, network diagnostics, scrollable tool panel - #95

Summary

Three things: a QR code to open the show on a phone, diagnostics that say why a phone can't, and a Patterns tab that stops eating the grid.

Scan to open (Show route). The bare LAN: 192.168.… text becomes a popover with a QR of that URL, a copy button, and a picker when the laptop holds several addresses. Nothing is persisted — the URLs come from BrainStatus.lanUrls (recomputed from live interfaces every status read) and the control isn't rendered while the brain is down. Ordering is rankLanUrls: 192.168/16 first, then 10/8, then 172.16/12, with 169.254 (DHCP never completed) last, so the address a phone is actually on leads instead of a docker bridge.

One Electron wrinkle: the laser UI is a native WebContentsView stacked above the page, so a popover overlapping it would be invisible. The route hides the view while the QR is open (visible: !sharing) and restores it on close.

Network doctor (Status → Advanced, and wavegrid doctor). The honest answer to "should the LAN URL work on the same wifi?" — the server does bind 0.0.0.0, so the URL is real, but a venue/guest network with client isolation blocks it anyway and a laptop cannot prove reachability by itself. So the report separates evidence from inference:

visitors.length > 0        → proven-reachable   (a real device loaded the show)
bindHost is loopback       → loopback-only
no interfaces              → no-network
a self-probe failed        → blocked-locally    (host firewall)
neighbours known and <= 1  → isolation-likely   (only the gateway is visible)
otherwise                  → unproven           ("scan the QR — that's the only proof")

The positive evidence is new: http-app.ts records non-loopback HTTP clients into a bounded (20) in-memory map surfaced as SystemStatus.lanVisitors, so "a phone reached the brain" becomes a fact rather than a guess. probeNetwork drops visitors whose address is one of our own interfaces — a browser on this laptop opening the LAN URL proves nothing. Neighbour discovery shells out to arp -an and reports neighboursKnown: false when that isn't available, so an unreadable table never reads as "nobody is there". verdictFor is pure and tested.

runningBind() is new because BrainStatus.url is deliberately the loopback URL the embedded UI loads; diagnostics need the actual bind host.

Patterns scroll (packages/ui). The bottom tool panel had no height cap and no internal scroll, so a tall tab pushed the grid off screen. It's now maxHeight: 50% with the content area flex-1 overflow-y-auto; the right-hand layout is unchanged.

Verified against a running show on this box: doctor printed proven-reachable for a real request over the LAN IP, and blocked-locally/unproven classifications are covered by tests. pnpm test, pnpm build, pnpm lint all pass.

Link to Devin session: https://app.devin.ai/sessions/972698f89f494b86828010666a002b8f
Requested by: @pyramation