feat: login rate limiting, network drivers in initfs

P2-2: Login rate limiting (userutils/login.rs):
- Tracks consecutive failures, resets on success
- 3+ failures: exponential delay up to 30 seconds
- Applies to both password and blank-password login paths

P2-3: Network stack in initfs (base-initfs + service files):
- Added e1000d, rtl8168d to base-initfs BINS
- 60_smolnetd.service: network stack in initfs
- 61_dhcpd.service: DHCP client in initfs
- Network available before switch_root

Part of COMPREHENSIVE-FIX-AND-IMPROVEMENT-PLAN Phases P2.

recipes/core/base-initfs/recipe.toml

@@ -35,7 +35,7 @@ virt_bins()
 
 x86_common_bins()
 {
-    BINS+=(ahcid ided ps2d usbhidd usbscsid usbhubd xhcid vesad)
+    BINS+=(ahcid ided ps2d usbhidd usbscsid usbhubd xhcid vesad e1000d rtl8168d)
     virt_bins
 }