Add ZVMA pre/post script recipe + env-dump examples

Adds a Kubernetes-ZVMA companion to the existing Windows-ZVM recipe:

- scripts/examples/zerto-zvma-send.ps1 - Zerto-side sender for both
  pre and post phases, packages the Zerto* env vars into a structured
  JSON body and POSTs to a {phase}-templated webhook URL.
- scripts/examples/zerto-receiver-notify.ps1 - server-side receiver
  that posts a Slack/Teams notification, with phase-aware formatting
  and ZertoForce highlighted on pre.
- scripts/examples/zerto-receiver-vm-healthcheck.ps1 - server-side
  receiver that pings + port-probes each VM in VmDisplayNames after
  failover and writes a per-run JSON report.
- scripts/examples/send-env-vars.ps1 + save-env-vars.ps1 - generic
  env-dump client/receiver pair (the diagnostic that surfaced what
  the ZVMA scripts-service container exposes).
- docs/recipes/zerto-zvma-pre-post.md - full walkthrough mirroring
  the existing Windows-ZVM recipe's structure.
- README.md and docs/README.md - link the new recipe and examples.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

scripts/examples/zerto-zvma-send.ps1

@@ -0,0 +1,74 @@
+<#
+.SYNOPSIS
+    Zerto pre/post script (ZVMA / Linux scripts-service edition). Reads the
+    Zerto-injected environment variables and POSTs them to a Webhook Server
+    endpoint as a structured JSON payload.
+
+.DESCRIPTION
+    Drop into a VPG's Recovery Scripts in the ZVM UI:
+        VPG settings -> Recovery -> Scripts -> Pre / Post Recovery Script
+        Path:       /app/scripts-files/zerto-zvma-send.ps1
+        Parameters: -Phase pre   (or -Phase post on the post-recovery slot)
+
+    Configure $WebhookUrl + $Bearer (or use the -WebhookUrl / -Bearer params
+    so one script file can serve multiple VPGs / endpoints).
+
+    Async by default - the call returns 202 in milliseconds and the actual
+    work runs in the webhook server's background, so the VPG sequence is
+    never blocked by slow downstream actions (DNS, notifications, etc.).
+
+.NOTES
+    The scripts-service container has pwsh 7 and curl available. This script
+    uses Invoke-RestMethod to keep things native to PowerShell.
+#>
+
+[CmdletBinding()]
+param(
+    [Parameter(Mandatory)]
+    [ValidateSet('pre', 'post')]
+    [string] $Phase,
+
+    [string] $WebhookUrl = 'http://192.168.50.250:8080/hook/zerto-{phase}',
+    [string] $Bearer     = '',
+    [int]    $TimeoutSec = 10
+)
+
+$ErrorActionPreference = 'Stop'
+
+# Resolve {phase} placeholder so one URL template can route to /hook/zerto-pre
+# and /hook/zerto-post. Plain URLs without the token work too.
+$url = $WebhookUrl.Replace('{phase}', $Phase)
+
+$payload = [ordered]@{
+    phase      = $Phase
+    capturedAt = (Get-Date).ToUniversalTime().ToString('o')
+    host       = $env:HOSTNAME       # scripts-service pod name
+    zerto      = [ordered]@{
+        vpgName               = $env:ZertoVPGName
+        internalVpgName       = $env:ZertoInternalVpgName
+        operation             = $env:ZertoOperation        # Test / Failover / Move / ...
+        force                 = $env:ZertoForce            # only meaningful pre
+        vmDisplayNames        = $env:VmDisplayNames        # comma-separated for multi-VM VPGs
+        hypervisorManagerIP   = $env:ZertoHypervisorManagerIP
+        hypervisorManagerPort = $env:ZertoHypervisorManagerPort
+        outputDir             = $env:ZertoOutputDir
+        workingDir            = $env:ZertoWorkingDir
+    }
+}
+
+$body = $payload | ConvertTo-Json -Depth 4 -Compress
+
+$headers = @{ 'Content-Type' = 'application/json' }
+if ($Bearer) { $headers['Authorization'] = "Bearer $Bearer" }
+
+try {
+    $resp = Invoke-RestMethod -Method Post -Uri $url -Headers $headers `
+        -Body $body -TimeoutSec $TimeoutSec
+    Write-Host "[$Phase] webhook accepted: $($resp | ConvertTo-Json -Compress)"
+}
+catch {
+    # Pre/post failures should not block the VPG operation. Log loudly and exit 0
+    # so Zerto's recovery sequence continues. Flip to `exit 1` if you want a
+    # webhook outage to fail the failover.
+    Write-Warning "[$Phase] webhook call failed: $($_.Exception.Message)"
+}