Live-data alerts: flag blocks running below plan

[ApocDev]

The bridge already syncs live production stats from the running game, and the factory view shows plan-vs-actual flows — but nothing is proactive: a starved or under-built block only surfaces if you go looking at the right page.

Behavior

• Compare each block's live output rate against its planned rate over a short window and flag blocks running below a threshold (e.g. under 90% of plan, configurable) — a badge on the block in the sidebar/factory view, plus a compact "underperforming blocks" strip on the factory page.
• Distinguish "below plan" from "no data" (block not built yet, bridge disconnected) so unbuilt plans don't scream red — availability/built state already syncs from the mod.
• Optional escalation later: surface the same flags in the in-game panel via the bridge, so alerts reach the player where they're actually looking.

This is deliberately the lightweight cousin of full time-series metrics (#2) — instantaneous plan-vs-actual with a threshold, no history storage. If #2 lands, alerting can grow sustained-window logic on top of it.

Part of the in-game integration epic #34.