[Knowledge] architecture-doc: ## Advisory Notes — Stage 1: Managed Identity - **[Architec...

## Knowledge Contribution

**Type:** New service
**File:** `knowledge/services/architecture-doc.md`
**Status:** NEW FILE — this knowledge file does not exist yet and must be created

### Context
## Advisory Notes — Stage 1: Managed Identity

- **[Architectural Trade-off]** A single shared identity across all Container Apps simplifies wiring but increases blast radius — if the identity's permissions are over-scoped in later stages, every service inherits that exposure. Consider per-service identities for production least-privilege isolation.

- **[Security]** No resource lock is applied to the managed identity. Accidental deletion would orphan all downstream RBAC assignments and break ev

### Rationale
## Advisory Notes — Stage 1: Managed Identity

- **[Architectural Trade-off]** A single shared identity across all Container Apps simplifies wiring but increases blast radius — if the identity's permissions are over-scoped in later stages, every service inherits that exposure. Consider per-service identities for production least-privilege isolation.

- **[Security]** No resource lock is applied to the managed identity. Accidental deletion would orphan all downstream RBAC assignments and break ev

### Content to Add
```
## Advisory Notes — Stage 1: Managed Identity

- **[Architectural Trade-off]** A single shared identity across all Container Apps simplifies wiring but increases blast radius — if the identity's permi
```

### Source
Build advisory review

### Required Knowledge File Sections
The new knowledge file MUST include ALL of these sections:
1. **Description** (one-line summary)
2. **When to Use** (scenarios and selection criteria)
3. **POC Defaults** (default SKU, tier, configuration)
4. **Terraform Patterns** (azapi_resource with RBAC)
5. **Bicep Patterns** (ARM template resources)
6. **Application Code** (Python, C#, Node.js — where applicable)
7. **Common Pitfalls** (deployment failures, misconfigurations)
8. **Production Backlog Items** (what changes for production)

Start with the requested knowledge/services/architecture-doc.md file and review the advisory notes in the issue. Create the knowledge entry with all eight required sections, covering managed identity usage, POC defaults, Terraform and Bicep patterns, applicable application code, pitfalls, and production backlog items.

Written by the indexing model from the issue text.