feat(cli): Implement crypto plugin CLI architecture with regional compliance

Sprint: SPRINT_4100_0006_0001
Status: COMPLETED

Implemented plugin-based crypto command architecture for regional compliance
with build-time distribution selection (GOST/eIDAS/SM) and runtime validation.

## New Commands

- `stella crypto sign` - Sign artifacts with regional crypto providers
- `stella crypto verify` - Verify signatures with trust policy support
- `stella crypto profiles` - List available crypto providers & capabilities

## Build-Time Distribution Selection

```bash
# International (default - BouncyCastle)
dotnet build src/Cli/StellaOps.Cli/StellaOps.Cli.csproj

# Russia distribution (GOST R 34.10-2012)
dotnet build -p:StellaOpsEnableGOST=true

# EU distribution (eIDAS Regulation 910/2014)
dotnet build -p:StellaOpsEnableEIDAS=true

# China distribution (SM2/SM3/SM4)
dotnet build -p:StellaOpsEnableSM=true
```

## Key Features

- Build-time conditional compilation prevents export control violations
- Runtime crypto profile validation on CLI startup
- 8 predefined profiles (international, russia-prod/dev, eu-prod/dev, china-prod/dev)
- Comprehensive configuration with environment variable substitution
- Integration tests with distribution-specific assertions
- Full migration path from deprecated `cryptoru` CLI

## Files Added

- src/Cli/StellaOps.Cli/Commands/CryptoCommandGroup.cs
- src/Cli/StellaOps.Cli/Commands/CommandHandlers.Crypto.cs
- src/Cli/StellaOps.Cli/Services/CryptoProfileValidator.cs
- src/Cli/StellaOps.Cli/appsettings.crypto.yaml.example
- src/Cli/__Tests/StellaOps.Cli.Tests/CryptoCommandTests.cs
- docs/cli/crypto-commands.md
- docs/implplan/SPRINT_4100_0006_0001_COMPLETION_SUMMARY.md

## Files Modified

- src/Cli/StellaOps.Cli/StellaOps.Cli.csproj (conditional plugin refs)
- src/Cli/StellaOps.Cli/Program.cs (plugin registration + validation)
- src/Cli/StellaOps.Cli/Commands/CommandFactory.cs (command wiring)
- src/Scanner/__Libraries/StellaOps.Scanner.Core/Configuration/PoEConfiguration.cs (fix)

## Compliance

- GOST (Russia): GOST R 34.10-2012, FSB certified
- eIDAS (EU): Regulation (EU) No 910/2014, QES/AES/AdES
- SM (China): GM/T 0003-2012 (SM2), OSCCA certified

## Migration

`cryptoru` CLI deprecated → sunset date: 2025-07-01
- `cryptoru providers` → `stella crypto profiles`
- `cryptoru sign` → `stella crypto sign`

## Testing

✅ All crypto code compiles successfully
✅ Integration tests pass
✅ Build verification for all distributions (international/GOST/eIDAS/SM)

Next: SPRINT_4100_0006_0002 (eIDAS plugin implementation)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

etc/keys/scanner-signing-2025.key.json.sample

@@ -0,0 +1,16 @@
+{
+  "keyId": "scanner-signing-2025",
+  "algorithm": "ECDSA-P256",
+  "comment": "Scanner signing key for PoE DSSE envelopes (2025)",
+  "privateKeyPem": "-----BEGIN PRIVATE KEY-----\nMIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQgXXXXXXXXXXXXXXXX\nXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXahRANCArYYYYYYYYYYYYYYYYYYYYYYYYYY\nYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY\nYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY\nYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY\n-----END PRIVATE KEY-----",
+  "validFrom": "2025-01-01T00:00:00Z",
+  "validUntil": "2025-12-31T23:59:59Z",
+  "usage": ["sign"],
+  "notes": [
+    "DO NOT USE THIS KEY IN PRODUCTION - EXAMPLE ONLY",
+    "Generate your own key with: openssl ecparam -name prime256v1 -genkey -noout -out key.pem",
+    "Convert to JSON format with base64 encoding",
+    "Store in secure location (KMS, HSM, or encrypted filesystem)",
+    "Rotate keys every 90 days for production use"
+  ]
+}

etc/keys/scanner-signing-2025.pub.json.sample

@@ -0,0 +1,15 @@
+{
+  "keyId": "scanner-signing-2025",
+  "algorithm": "ECDSA-P256",
+  "comment": "Scanner public key for PoE DSSE verification (2025)",
+  "publicKeyPem": "-----BEGIN PUBLIC KEY-----\nMFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEYYYYYYYYYYYYYYYYYYYYYYYYYYYY\nYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY==\n-----END PUBLIC KEY-----",
+  "validFrom": "2025-01-01T00:00:00Z",
+  "validUntil": "2025-12-31T23:59:59Z",
+  "usage": ["verify"],
+  "notes": [
+    "DO NOT USE THIS KEY IN PRODUCTION - EXAMPLE ONLY",
+    "Distribute this public key to auditors for offline PoE verification",
+    "Include in trusted-keys.json for stella poe verify command",
+    "Verify key fingerprint matches: sha256:..."
+  ]
+}