Add back navigation links to edit pages

Added back navigation links at the top of all edit/new pages to
improve UX and make it easier to navigate back to previous pages.

Changes:
- Added back link to equipment edit/new pages
  - Edit: goes back to equipment detail page
  - New: goes back to equipment list
- Added back link to site edit/new pages
  - Edit: goes back to site detail page
  - New: goes back to sites list
- Links styled with arrow icon and subtle hover effect
- Added error handling to Counter64 decoder with try/rescue

The back links appear above the page header and provide clear
navigation context for users.

lib/towerops/snmp/poller_worker.ex

@@ -246,29 +246,38 @@ defmodule Towerops.Snmp.PollerWorker do
 
   defp decode_snmp_value(value) when is_binary(value) do
     # Try to decode based on byte size
-    case byte_size(value) do
-      8 ->
-        # Standard Counter64 (8 bytes, big-endian unsigned integer)
-        <<counter::unsigned-big-integer-size(64)>> = value
-        counter
+    try do
+      case byte_size(value) do
+        8 ->
+          # Standard Counter64 (8 bytes, big-endian unsigned integer)
+          <<counter::unsigned-big-integer-size(64)>> = value
+          counter
 
-      16 ->
-        # Some SNMP implementations return 16-byte values
-        # Try reading last 8 bytes as Counter64
-        <<_prefix::binary-size(8), counter::unsigned-big-integer-size(64)>> = value
-        counter
+        16 ->
+          # Some SNMP implementations return 16-byte values
+          # Try reading last 8 bytes as Counter64
+          <<_prefix::binary-size(8), counter::unsigned-big-integer-size(64)>> = value
+          counter
 
-      size when size > 8 ->
-        # Large binary, try reading last 8 bytes
-        offset = size - 8
-        <<_prefix::binary-size(offset), counter::unsigned-big-integer-size(64)>> = value
-        Logger.debug("Decoded #{size}-byte SNMP value as Counter64 from last 8 bytes: #{counter}")
-        counter
+        size when size > 8 ->
+          # Large binary, try reading last 8 bytes
+          offset = size - 8
+          <<_prefix::binary-size(offset), counter::unsigned-big-integer-size(64)>> = value
+          Logger.debug("Decoded #{size}-byte SNMP value as Counter64 from last 8 bytes: #{counter}")
+          counter
 
-      _ ->
-        # Unknown binary format or too small
-        Logger.warning(
-          "Unknown SNMP binary value format, size: #{byte_size(value)}, bytes: #{inspect(value)}"
+        _ ->
+          # Unknown binary format or too small
+          Logger.warning(
+            "Unknown SNMP binary value format, size: #{byte_size(value)}, bytes: #{inspect(value)}"
+          )
+
+          nil
+      end
+    rescue
+      error ->
+        Logger.error(
+          "Failed to decode SNMP binary value (size: #{byte_size(value)}): #{inspect(error)}, bytes: #{inspect(value)}"
         )
 
         nil

lib/towerops_web/live/equipment_live/form.html.heex

@@ -1,4 +1,18 @@
 <Layouts.authenticated flash={@flash} current_organization={@organization}>
+  <div class="mb-4">
+    <.link
+      navigate={
+        if @live_action == :edit,
+          do: ~p"/orgs/#{@organization.slug}/equipment/#{@equipment.id}",
+          else: ~p"/orgs/#{@organization.slug}/equipment"
+      }
+      class="inline-flex items-center gap-1 text-sm text-zinc-600 hover:text-zinc-900 dark:text-zinc-400 dark:hover:text-zinc-100"
+    >
+      <.icon name="hero-arrow-left" class="h-4 w-4" />
+      {if @live_action == :edit, do: "Back to Equipment", else: "Back to Equipment List"}
+    </.link>
+  </div>
+
   <.header>
     {@page_title}
     <:subtitle>

lib/towerops_web/live/site_live/form.html.heex

@@ -1,4 +1,18 @@
 <Layouts.authenticated flash={@flash} current_organization={@organization}>
+  <div class="mb-4">
+    <.link
+      navigate={
+        if @live_action == :edit,
+          do: ~p"/orgs/#{@organization.slug}/sites/#{@site.id}",
+          else: ~p"/orgs/#{@organization.slug}/sites"
+      }
+      class="inline-flex items-center gap-1 text-sm text-zinc-600 hover:text-zinc-900 dark:text-zinc-400 dark:hover:text-zinc-100"
+    >
+      <.icon name="hero-arrow-left" class="h-4 w-4" />
+      {if @live_action == :edit, do: "Back to Site", else: "Back to Sites"}
+    </.link>
+  </div>
+
   <.header>
     {@page_title}
     <:subtitle>