fleet-manager ui: readability + reboot-now

- Contrast: lighten the muted/faint text tokens (AA on the hull panels) and make
  Monitor host-card data values bright ink against dim faint labels, so version/
  tmpfs/seen details read clearly on the blue-grey panels (was grey-on-grey).
- Lifecycle: reboot selector now offers none | now | at... — 'now' sets
  reboot_at to the current time (agent reboots on reconcile); still confirm-gated
  as a high-consequence action.

serving/fleet-manager/ui/src/app.css

@@ -27,10 +27,10 @@
   --color-red:        #FF3B2F;  /* alert / out-of-range */
   --color-amber-hot:  #FF8A3D;  /* caution band */
 
-  /* text */
-  --color-ink:   #E9EEF6;  /* primary text (warm off-white) */
-  --color-muted: #7E8DA3;  /* secondary text, labels */
-  --color-faint: #46566E;  /* tertiary, timestamps, meta */
+  /* text — tuned for legibility on the dark hull panels (AA on hull2) */
+  --color-ink:   #EAF1F9;  /* primary text (warm off-white) */
+  --color-muted: #AEC0D6;  /* secondary text / data values — clearly readable */
+  --color-faint: #7688A2;  /* tertiary labels, timestamps, meta */
 
   /* hairlines */
   --color-line:  #223146;  /* structural */

serving/fleet-manager/ui/src/pages/Lifecycle.svelte

@@ -10,6 +10,7 @@
   let selected = $state(null)
   let busy = $state(false)
   let confirmOpen = $state(false)
+  let rebootMode = $state('none') // none | now | at
   let form = $state({ target_version: '', kiosk_url: '', reboot_at: '', drain: false })
 
   async function load() {
@@ -24,6 +25,7 @@
   function pick(h) {
     selected = h
     okMsg = ''
+    rebootMode = 'none'
     form = {
       target_version: h.desired?.target_version || '',
       kiosk_url: h.desired?.kiosk_url || '',
@@ -31,9 +33,8 @@
       drain: !!h.desired?.drain,
     }
   }
-  let consequence = $derived(
-    [form.drain ? 'DRAIN this host' : null, form.reboot_at ? 'schedule a REBOOT' : null].filter(Boolean).join(' and ')
-  )
+  let rebootConseq = $derived(rebootMode === 'now' ? 'REBOOT it NOW' : rebootMode === 'at' && form.reboot_at ? 'schedule a REBOOT' : null)
+  let consequence = $derived([form.drain ? 'DRAIN this host' : null, rebootConseq].filter(Boolean).join(' and '))
   async function apply() {
     confirmOpen = false
     busy = true
@@ -44,7 +45,8 @@
       kiosk_url: form.kiosk_url || undefined,
       drain: form.drain,
     }
-    if (form.reboot_at) body.reboot_at = new Date(form.reboot_at).toISOString()
+    if (rebootMode === 'now') body.reboot_at = new Date().toISOString()
+    else if (rebootMode === 'at' && form.reboot_at) body.reboot_at = new Date(form.reboot_at).toISOString()
     try {
       const res = await api.put(`/api/hosts/${selected.identity.cert_serial}/desired`, body)
       okMsg = res.pushed_live ? 'applied — pushed to the live host' : 'applied — host reconciles on next connect'
@@ -58,7 +60,7 @@
   }
   function submit() {
     // Gate destructive changes behind a confirm; a plain version/URL change applies directly.
-    if (form.drain || form.reboot_at) confirmOpen = true
+    if (form.drain || rebootMode === 'now' || (rebootMode === 'at' && form.reboot_at)) confirmOpen = true
     else apply()
   }
   $effect(() => {
@@ -94,10 +96,19 @@
             <span class="tag">kiosk url</span>
             <input class="mt-1 w-full rounded border border-line bg-void2 px-2 py-1.5 text-sm text-ink" bind:value={form.kiosk_url} placeholder="http://boot.fleet.lab/kiosk/" />
           </label>
-          <label class="block">
-            <span class="tag">reboot at (optional)</span>
-            <input type="datetime-local" class="mt-1 w-full rounded border border-line bg-void2 px-2 py-1.5 text-sm text-ink" bind:value={form.reboot_at} />
-          </label>
+          <div class="block">
+            <span class="tag">reboot</span>
+            <div class="mt-1 flex items-center gap-2">
+              <select class="rounded border border-line bg-void2 px-2 py-1.5 text-sm {rebootMode !== 'none' ? 'text-violet-soft' : 'text-ink'}" bind:value={rebootMode}>
+                <option value="none">none</option>
+                <option value="now">now</option>
+                <option value="at">at…</option>
+              </select>
+              {#if rebootMode === 'at'}
+                <input type="datetime-local" class="flex-1 rounded border border-line bg-void2 px-2 py-1.5 text-sm text-ink" bind:value={form.reboot_at} />
+              {/if}
+            </div>
+          </div>
           <label class="mt-4 flex items-center gap-2">
             <input type="checkbox" bind:checked={form.drain} />
             <span class="font-display text-sm text-violet-soft">drain (stop taking work)</span>

serving/fleet-manager/ui/src/pages/Monitor.svelte

@@ -64,7 +64,7 @@
             <StatePill state={h.online ? healthState(h.health) : 'off'} />
           </div>
           <div class="tag mt-0.5">{shortSerial(h.identity.cert_serial)} · {h.binding?.location || 'unbound'}</div>
-          <div class="mt-2 grid grid-cols-3 gap-2 font-mono text-xs text-muted">
+          <div class="mt-2 grid grid-cols-3 gap-2 font-mono text-xs text-ink">
             <div><span class="text-faint">ver </span>{h.version?.image_version || '—'}{#if drift(h)}<span class="text-amber-hot"> ⇢ {h.desired.target_version}</span>{/if}</div>
             <div><span class="text-faint">tmpfs </span>{pct(h.health?.tmpfs_used_pct)}</div>
             <div><span class="text-faint">seen </span>{h.online ? 'live' : relTime(h.last_seen)}</div>