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/coding_guidelines.instructions.md

@@ -0,0 +1,43 @@
+# Coding Guidelines Instructions
+
+## Naming
+- Manager: *Manager
+- Controller: *Controller
+- Entities: Singular Substantive
+- Negative IDs: temporäre Objekte
+
+## Style
+- 4 Spaces
+- Logger statt System.out
+- Deutsche UI-Texte, Englisch im Code
+
+## Error Handling
+- Log + Rückgabe (bestehend); für neue komplexe Logik optional BusinessException
+
+## Persistenz
+- Neue Entity: id == null vor persist
+- refresh(entity) nutzen um Lazy Collections zu initialisieren
+
+## Transaktionen
+- Schreibmethoden: @Transactional (oder rely auf EJB Container)
+
+## Performance
+- Sammeloperationen: saveAll(Collection<T>)
+
+## UI
+- PrimeFaces Dialoge schließen mit closeDialogs
+- Negative IDs in Listen bis Sammelspeichern
+
+## PDF
+- Neue Funktionen nur mit iText7 API
+
+## Tests (Empfehlung)
+- CRUD Manager Tests
+- Klon & Fragebogen Zuordnung
+
+## Anti-Pattern
+- Logik nicht direkt im Controller wenn generell wiederverwendbar
+- Keine duplizierten Query Strings -> Named Queries
+
+---
+Aktualisiert: 2025-10-20