[User Story] - Integrate Entra ID for User authentication and authorization

**Description**
Brief summary of the problem or enhancement. What is happening or what is needed? Focus on user impact, not implementation details.

**Current Behavior**
Describe what currently happens. Include examples, logs, or snippets if helpful.

**Acceptance Criteria**
List clear, testable outcomes. Example:
- [ ] Credit card numbers in agent responses are masked (only last 4 digits remain)
- [ ] Middleware applies across all agents generating text
- [ ] Unit tests cover detection and non-detection scenarios

**Design Considerations**
High-level approach. Mention patterns (e.g., agent middleware), data flow, constraints, and any alternatives rejected. Do NOT paste full code unless essential.

**Main Affected Modules and/or Classes**
List exact file paths or module names. Example:
- app/copilot/app/agents/azure_chat/account_agent.py
- app/copilot/app/agents/azure_chat/payment_agent.py

**References**
Link to docs, ADRs, samples, related issues. Example:
- Agent middleware docs:
- Sample middleware implementation:

## Optional
**Security & Privacy (optional)**
Data masking, logging considerations, PII handling, compliance notes.

**Risks & Mitigations (optional)**
Potential side effects (e.g., false positives masking numbers that aren't cards) and mitigation strategies.

**Open Questions (optional)**
Items needing clarification before implementation.

**Additional Context (optional)**
Supporting info: screenshots, sample responses, logs, reproduction steps.

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*Migrated from: https://github.com/Azure-Samples/agent-openai-python-banking-assistant/issues/11*

Der Issue-Text ist noch eine unausgefüllte Vorlage und nennt keine Dateien, Module, Einstiegspunkte, Akzeptanzkriterien oder Referenzen. Beginne damit, den Authentifizierungs- und Autorisierungsablauf im Repository zu identifizieren und das beabsichtigte Verhalten von Entra ID, die betroffenen Komponenten sowie eine testbare Definition of Done zu klären, bevor du mit der Implementierung beginnst.

Vom Indexierungsmodell aus dem Issue-Text verfasst.