Add multipath.conf for Pure FlashArray to Talos worker nodes

- Add /etc/multipath.conf file creation in worker patches
- Configuration optimized for Pure FlashArray iSCSI
- Required for PX-CSI node pods to start successfully
- Blacklists Portworx virtual devices (pxd*)

Ref: Portworx → democratic-csi migration Phase 3

talos/talhelper/talconfig.yaml

@@ -155,6 +155,42 @@ worker:
           net.ipv4.conf.all.arp_announce: "2"
           net.ipv4.conf.all.arp_ignore: "1"
 
+    - |-
+      machine:
+        files:
+          - path: /etc/multipath.conf
+            permissions: 0644
+            op: create
+            content: |
+              # Multipath configuration for Pure Storage FlashArray
+              defaults {
+                  polling_interval 10
+                  find_multipaths yes
+                  user_friendly_names no
+              }
+              
+              devices {
+                  device {
+                      vendor "PURE"
+                      product "FlashArray"
+                      path_selector "service-time 0"
+                      path_grouping_policy group_by_prio
+                      prio alua
+                      path_checker tur
+                      fast_io_fail_tmo 10
+                      user_friendly_names no
+                      no_path_retry 0
+                      hardware_handler "1 alua"
+                      dev_loss_tmo 600
+                      failback immediate
+                  }
+              }
+              
+              blacklist {
+                  devnode "^pxd[0-9]*"
+                  devnode "^pxd.*"
+              }
+
 # ─── Nodes ───────────────────────────────────────────────────────────────────
 nodes:
   # ── Control plane ──────────────────────────────────────────────────────────