Add a Pester test suite for the collectors

84 tests in collectors/tests, run with Invoke-CollectorTests.ps1 (~15 s,
PowerShell 7.2+ and Pester 5.5+):

- Module.Tests: the shared module (property lookup, time format,
  config/lookback, sent-run state and pruning, dry runs, exit codes,
  401 detection)
- Veeam/Mars/Wsb/Vb365.Tests: each collector run in its own process
  against its mock and a stand-in ingest API, asserting the behaviours
  confirmed on real servers: VBR 13 live schedule, copy jobs, MARS UTC
  times and ErrorCode 0, WSB culture-formatted times and nested VMs,
  VB365 organization mapping, log prefixes and retries, state and
  resending, rejected keys
- Installers.Tests: config, files and scheduled task from each
  installer, with stand-ins for icacls / Task Scheduler / the key prompt

Collectors run under the test runner's PowerShell, or another shell via
-CollectorShell (e.g. powershell.exe, to test under Windows PowerShell
5.1 like the MARS, WSB and VB365 servers). The mocks take their "now"
from MOCK_NOW so expectations can't drift with the clock; the WSB mock
gains -RunningJobFinished for the running-to-finished case.

Each of 12 past bugs, put back one at a time, fails the test for its
behaviour (and the runner exits 1).

Co-Authored-By: Claude Opus 5.5 <[email protected]>

collectors/wsb/tests/MockWsb.ps1

@@ -6,11 +6,13 @@
 #
 #   . ./tests/MockWsb.ps1                  # nothing running
 #   . ./tests/MockWsb.ps1 -WithRunningJob  # a backup in progress
+#   . ./tests/MockWsb.ps1 -RunningJobFinished  # that same backup, now finished
 #   ./Send-WsbBackupStatus.ps1 -ConfigPath ./my-test-config.json -DryRun
-param([switch]$WithRunningJob)
+param([switch]$WithRunningJob, [switch]$RunningJobFinished)
 
 # Fixed to the top of the hour so repeated runs see the same jobs
-$now = Get-Date -Minute 0 -Second 0 -Millisecond 0
+# MOCK_NOW (ISO 8601, set by the test suite) pins the time everything is relative to
+$now = if ($env:MOCK_NOW) { [datetime]$env:MOCK_NOW } else { Get-Date -Minute 0 -Second 0 -Millisecond 0 }
 
 # Same format as the real cmdlet: short date + short time in the current culture
 function Format-WbTime($Value) {
@@ -83,6 +85,9 @@ $global:MockWsbPrevious = @(
     (New-MockJob 'Recovery' $now.AddHours(-5) $now.AddHours(-4) 'Completed'),  # a restore: must be ignored
     (New-MockJob 'Backup' $now.AddDays(-5) $now.AddDays(-5).AddHours(1) 'Completed')  # outside 48h lookback
 )
+if ($RunningJobFinished) {
+    $global:MockWsbPrevious += New-MockJob 'Backup' $now.AddMinutes(-10) $now.AddMinutes(-2) 'Completed' -Items @(New-VmList 10GB)
+}
 
 $global:MockWsbSummary = [pscustomobject]@{
     NextBackupTime           = $now.Date.AddHours(21).AddDays($(if ($now.Hour -ge 21) { 1 } else { 0 }))