dashboard: surface slot eviction state (pin/LRU, last-eviction reason, host free vs floor)

[thinmintdev]

Context

Part of the eviction epic fixing the 2026-06-19 CT105→host OOM. Slices 1 & 2 make reclaim happen silently; this makes it visible so an operator can see why a slot cold-started and how close the host is to the pressure floor.

What to build

Surface eviction state on the dashboard slots page: per-slot pinned vs LRU-eligible status and idle_timeout_s, the last-eviction event per slot (what was unloaded and why — TTL vs pressure), and the live host free RAM vs evict_pressure_mb floor (with a near-threshold indicator). End-to-end: an operator watching the page sees a slot get evicted under pressure, sees free-RAM recover above the floor, and sees the slot wake on its next request.

Acceptance criteria

• Slots page shows each slot's pin/LRU-eligible status and effective idle_timeout_s
• Last-eviction event (slot, reason: TTL | pressure, timestamp) is visible per slot
• Live host free-RAM vs the pressure floor is displayed with a near-threshold cue
• An eviction → wake cycle is observable on the page without a manual refresh
• Read-only surfacing — no new control that triggers eviction from the UI

Blocked by

• slots: TTL-driven hard eviction — idle sweep unloads past idle_timeout_s (pinning via 0) #902 (eviction must exist to surface its state)