Reduce host capacity headroom and remove learned usage padding

src/routes/hosts/[id]/+page.svelte

@@ -58,7 +58,7 @@
         </section>
         {#if !cleaning}<section class="panel"><h2>Automatic host setup</h2><HostPreparation {host} /></section>{/if}
         {#if calibration}<section class="panel"><h2>Learned server capacity</h2>
-            <p>Allowances update from observed container usage with 25% headroom. Startup and running usage are tracked separately.</p>
+            <p>Allowances update from observed container usage. Hosts reserve 5% CPU and 500 MB of memory. Startup and running usage are tracked separately.</p>
             <dl>{#each ['startup', 'running'] as phase}{@const allowance = calibration[phase as keyof CapacityCalibration]}
                 <dt>{phase === 'startup' ? 'Starting a server' : 'Running a server'}</dt>
                 <dd>{allowance.cpuCores.toFixed(2)} CPU cores · {bytes(allowance.memoryBytes)} · {allowance.source === 'host' ? 'Learned on this host' : allowance.source === 'fleet' ? 'Learned from the fleet' : 'Calibrating; temporary allowance'} ({allowance.samples} samples)</dd>