fix: P2+P3 bug fixes, hardening, and cleanup (18 files)

Bug fixes:
- Add applyEnvOverrides to LoadFromBytes (M05)
- Set state=failed on compose-up failure in selfupdate (M16)
- Clamp usableMB to min 0 in memory check (M22)
- Remove "manual" schedule from triggerAllCrossBackups (M23)
- Add mmcblk device handling for partition paths (M21)
- Fix stripPartition for mmcblk devices (L25)
- Fix TruncateStr for UTF-8 and negative maxLen (L05/L06)
- Fix AllDone to return false for empty restore plans (L14)
- Fix PushOnce to return actual errors (L39)
- Restore pending events on save failure in DrainPendingEvents (M03)
- Add duplicate check in AddStoragePath (M04)
- Call CleanupTempMounts after drive scan (H13)
- Log SetStep save errors (M25)

Hardening:
- Guard scheduler Start() against double-start (M14)
- Acquire mutex in scheduler Stop() before reading cancel (L24)
- Cap log lines parameter to 10000 (L31)
- Require POST for logout (L32)
- Use sync.Once for Server.Close() (L49)
- Panic on crypto/rand.Read failure in setup CSRF (L40)
- Validate Bearer token against Hub API key in CSRF (H16 fix)
- Replace custom hasPrefix with strings.HasPrefix (L13)
- Replace simpleHash with crc32.ChecksumIEEE (L48)

Cleanup:
- Remove dead imageName function (L02)
- Remove dead detectHostIPViaRoute function (L03)
- Rename shadowed copy variable to cp (L07)
- Copy DefaultEnabledEvents in GetNotificationPrefs early return (L09)
- Update BUGHUNT.md with comprehensive audit results

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

controller/internal/setup/network.go

@@ -3,7 +3,6 @@ package setup
 import (
 	"net"
 	"os"
-	"os/exec"
 	"strings"
 )
 
@@ -11,46 +10,17 @@ import (
 // Inside a Docker container, the network interfaces only show the bridge IP
 // (e.g. 172.18.0.4), which is useless for users. Instead, we:
 // 1. Check HOST_IP env var (set by docker-compose.yml)
-// 2. Try to detect the Docker host gateway via `ip route`
-// 3. Fall back to interface enumeration as last resort
+// 2. Fall back to interface enumeration as last resort
 func DetectLocalIPs() []string {
 	// Option 1: explicit HOST_IP from environment
 	if hostIP := os.Getenv("HOST_IP"); hostIP != "" {
 		return []string{hostIP}
 	}
 
-	// Option 2: detect Docker host gateway IP via default route
-	// Inside a container, `ip route | grep default` gives the host gateway.
-	// Then we check the host's IP by looking at what IP routes to that gateway.
-	if ip := detectHostIPViaRoute(); ip != "" {
-		return []string{ip}
-	}
-
-	// Option 3: fallback to interface enumeration (works on bare metal)
+	// Option 2: fallback to interface enumeration (works on bare metal)
 	return detectInterfaceIPs()
 }
 
-// detectHostIPViaRoute tries to find the Docker host's LAN IP.
-// Inside a container, the default gateway is the Docker host.
-// We read /host-etc/hostname or use the gateway as a hint.
-func detectHostIPViaRoute() string {
-	// Try: ip route get 1.0.0.0 — shows the source IP used for routing
-	out, err := exec.Command("ip", "route", "get", "1.0.0.0").Output()
-	if err != nil {
-		return ""
-	}
-	// Output: "1.0.0.0 via 172.18.0.1 dev eth0 src 172.18.0.4"
-	// The gateway (172.18.0.1) is the Docker host — but that's the bridge IP.
-	// We need the host's actual LAN IP.
-
-	// Better approach: read /proc/net/route or parse `ip route` for the gateway,
-	// then the gateway itself is the Docker host — but we need its external IP.
-	// Since we can't easily get the host's LAN IP from inside the container,
-	// return empty and let the fallback handle it or rely on HOST_IP env.
-	_ = out
-	return ""
-}
-
 func detectInterfaceIPs() []string {
 	ifaces, err := net.Interfaces()
 	if err != nil {