fix: P0+P1 critical bug fixes across controller (24 files)

Concurrency fixes:
- Deep-copy stacks in GetStack/GetStacks to prevent shared state mutation (C04)
- Add per-state mutex to watchdog pathProbeState (C05)
- Guard MetricsCollector.Start() with sync.Once against double-start (C06)
- Hold diskJobMu across entire raw mount operation (C07)
- Add mutex to SetEncryptionKey (C08), MigrateEncryption write lock (H03)
- Use sync.Once for sync.Stop() channel close (H08)
- Set syncing=true before releasing lock in TriggerSync (H09)
- Deep-copy lastDBDump/lastBackup in GetFullStatus (H11)
- Add WaitGroup for stderr goroutine in MigrateDrive (H19)
- Add mutex to SetBackupRunningCheck (M18)

Security fixes:
- Validate Bearer token against Hub API key in CSRF middleware (H16)
- Validate backup paths start with expected prefix in RemoveStack (M12)
- Guard uuid[:8] slice with length check (H20)
- Parse fstab fields exactly for mount target matching (H21)

Bug fixes:
- Use decrypted env vars for compose deploy (C01)
- Log decrypt failures in DecryptMap instead of swallowing (C02)
- Move Deployed=false inside lock in runComposeDeploy (C03)
- Fix activeDrives() to skip disconnected drives (H02)
- Fix Snapshot() stderr extraction from exec.ExitError (H01)
- Check unlockCmd.Run() error in restic (H01)
- Buffer template rendering via bytes.Buffer (H07)
- Thread context.Context through cloudflare client (H10)
- Fix leaf-name collision detection in cross-drive backup (H15)
- Add nil check for crossDriveRunner (H17)
- Use strings.TrimSpace instead of slice on command output (H18)
- Make SaveAppConfig atomic with write-to-tmp+rename (H04)
- Pass encKey on deploy failure SaveAppConfig (H05)
- Fix IPv6 address format in TCP health probe

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

controller/internal/cloudflare/zone.go

@@ -1,6 +1,7 @@
 package cloudflare
 
 import (
+	"context"
 	"encoding/json"
 	"fmt"
 	"net/url"
@@ -14,9 +15,9 @@ type zone struct {
 
 // GetZoneID resolves the Cloudflare zone ID for a domain.
 // It tries the exact domain first, then strips subdomains progressively.
-func (c *Client) GetZoneID(domain string) (string, error) {
+func (c *Client) GetZoneID(ctx context.Context, domain string) (string, error) {
 	// Try exact domain first (e.g., "demo-felhom.eu")
-	id, err := c.lookupZone(domain)
+	id, err := c.lookupZone(ctx, domain)
 	if err != nil {
 		return "", err
 	}
@@ -31,7 +32,7 @@ func (c *Client) GetZoneID(domain string) (string, error) {
 			if parent == "" {
 				break
 			}
-			id, err = c.lookupZone(parent)
+			id, err = c.lookupZone(ctx, parent)
 			if err != nil {
 				return "", err
 			}
@@ -45,9 +46,9 @@ func (c *Client) GetZoneID(domain string) (string, error) {
 }
 
 // lookupZone queries the CF API for a zone by name.
-func (c *Client) lookupZone(name string) (string, error) {
+func (c *Client) lookupZone(ctx context.Context, name string) (string, error) {
 	path := "/zones?name=" + url.QueryEscape(name) + "&status=active"
-	resp, err := c.do("GET", path, nil)
+	resp, err := c.do(ctx, "GET", path, nil)
 	if err != nil {
 		return "", fmt.Errorf("lookup zone %q: %w", name, err)
 	}