chore(java): consolidate mss-failsafe to single canonical copy

Replace the stale multi-module java/mss-failsafe skeleton (old user-management
prototype) with the active single-module machine-safety inspection app that was
living in its own standalone repo at the repo root.

- Remove old java/mss-failsafe/ multi-module tree (mss, userdata, userManagement,
  mssfailsafe.datalayer, mssfailsafeWeblayer) incl. committed build artifacts
- Add the active app (PrimeFaces 11 / JSF 2.3 / Hibernate 5.6 / iText / POI)
  flattened into java/mss-failsafe/ as the only mss-failsafe in git
- Working tree captured = master tip 2a142b5 + in-progress uncommitted work
  (incl. .github/*.instructions.md AI-context files)
- Archive the standalone repo's 33-commit history in GIT_HISTORY_ARCHIVE.md
  since its .git was not migrated

This is the source of truth / base for the upcoming upgraded rewrite.

java/mss-failsafe/.github/security_area_domain.instructions.md

@@ -0,0 +1,39 @@
+# Security Area Domain Instructions
+
+## Entities
+- SecurityArea
+- SecurityDevice / DangerPoint / SwitchingDevice
+- SecurityAreaQuestionnaire (Wrapper) + Questionaire
+
+## Operations
+- cloneArea(SecurityArea)
+- addQuestionnaireToSecurityArea(area, questionnaire)
+- removeQuestionnaireFromSecurityArea(area, wrapper)
+- getAvailableQuestionnaires(area)
+- reloadWithQuestionnaires(area)
+
+## Workflow (Add Questionnaire)
+1. Area laden (falls id > 0)
+2. Wrapper erstellen & area setzen
+3. Persist Wrapper, merge Area
+4. Refresh im Controller
+
+## Deletion Pattern
+- Beziehungen lösen (Kinder area = null setzen)
+- Kinder entfernen (Manager.removeAllIn)
+- Area per Named Query löschen
+
+## Edge Cases
+- Duplicate questionnaire by name -> aktuell Filter per Name
+- Verbesserung: Filter per ID
+
+## Klonen
+- Persistente Quelle re-laden, initialisieren
+- Copy-Konstruktor & alle Child IDs auf null
+
+## Verbesserungen
+- CascadeSettings prüfen
+- Bean Validation einsetzen
+
+---
+Aktualisiert: 2025-10-20