docserver: self-healing Task Scheduler config + docs

Companion to the worker MinIO-retry fix. Makes the worker auto-recover from
process death (crash, manual kill, missed boot trigger), not just MinIO outages.

- start_worker.bat: propagate Python's exit code (exit /b %rc%) so Task
  Scheduler can actually detect a failed run (it previously always exited 0).
- reconfigure_task.ps1 (new): re-registers PW-DocserverWorker with
  RestartCount=99 / 1-min interval, StartWhenAvailable, and two triggers —
  AtStartup plus a 5-min repeating trigger with MultipleInstances=IgnoreNew, so
  a dead worker relaunches within ~5 min and never double-runs. Idempotent.
- install.ps1: same self-healing settings for fresh installs.
- Verified on the box: killed the worker -> task relaunched it; firing again
  while running stayed at one instance.

Docs updated to match reality:
- docserver/README.md: new 'Reliability / self-healing' section.
- document-generation.md: corrected the stale 'Flask DocServer :5050 / HTTP'
  description to the actual MinIO outbound-only transport.
- e2e-test-plan.md: removed the outdated 'Word COM fails under SYSTEM / requires
  RDP after every reboot' limitation; now self-healing under SYSTEM session 0.
- infrastructure.md: fixed VM spec (Win Server 2019, Word 16.0, Python 3.13,
  SSH port 22422) + self-healing note.
- architecture.md / formation-system.md: trigger + self-healing details.

docserver/install.ps1

@@ -166,11 +166,18 @@ $action = New-ScheduledTaskAction `
     -Argument "/c `"$AppDir\start_worker.bat`"" `
     -WorkingDirectory $AppDir
 
-$trigger = New-ScheduledTaskTrigger -AtStartup
+# Two triggers for self-healing: at boot, plus a repeating 5-minute safety net
+# that relaunches the worker if its process ever dies (crash, manual kill, or a
+# missed boot trigger). MultipleInstances=IgnoreNew keeps it to one instance.
+$atStartup = New-ScheduledTaskTrigger -AtStartup
+$repeat    = New-ScheduledTaskTrigger -Once -At (Get-Date) `
+    -RepetitionInterval (New-TimeSpan -Minutes 5)
+try { $repeat.Repetition.Duration = 'P3650D' } catch {}  # some builds need an explicit long duration
+$trigger = @($atStartup, $repeat)
 
 $settings = New-ScheduledTaskSettingsSet `
     -ExecutionTimeLimit (New-TimeSpan -Hours 0) `
-    -RestartCount 10 `
+    -RestartCount 99 `
     -RestartInterval (New-TimeSpan -Minutes 1) `
     -StartWhenAvailable `
     -MultipleInstances IgnoreNew `