feat(enterprise): Phase 14 — API Key Management + SSO/SAML 2.0

- ApiKey model (SHA-256 hash, prefix, scopes, expiry) + Alembic migration (b040ent)
- SsoConfig model for SAML 2.0 IdP settings (attribute mapping, auto-provision)
- API key auth integrated into get_current_user (aegis_ prefix detection)
- Routers: /api/v1/api-keys (full CRUD + revoke) and /api/v1/sso (metadata, login, callback, config)
- python3-saml added to requirements; Dockerfile adds libxmlsec1-dev for SAML XML signing
- QA script: 52 assertions covering key lifecycle, API key auth, SSO config

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/schemas/api_key_schema.py

@@ -0,0 +1,68 @@
+"""Phase 14: API Key Pydantic schemas."""
+
+from __future__ import annotations
+
+from datetime import datetime
+from typing import List, Optional
+from uuid import UUID
+
+from pydantic import BaseModel, Field, field_validator
+
+from app.models.api_key import VALID_SCOPES
+
+
+class ApiKeyCreate(BaseModel):
+    name:        str             = Field(..., min_length=1, max_length=200)
+    description: Optional[str]  = None
+    scopes:      List[str]       = Field(default=["read"])
+    expires_at:  Optional[datetime] = None
+
+    @field_validator("scopes")
+    @classmethod
+    def validate_scopes(cls, v: list) -> list:
+        invalid = set(v) - VALID_SCOPES
+        if invalid:
+            raise ValueError(f"Invalid scopes: {invalid}. Valid: {VALID_SCOPES}")
+        if not v:
+            raise ValueError("At least one scope is required")
+        return v
+
+
+class ApiKeyOut(BaseModel):
+    """Safe representation — never exposes key_hash."""
+    id:           UUID
+    name:         str
+    description:  Optional[str] = None
+    key_prefix:   str
+    user_id:      UUID
+    scopes:       List[str]
+    last_used_at: Optional[datetime] = None
+    expires_at:   Optional[datetime] = None
+    is_active:    bool
+    created_at:   Optional[datetime] = None
+
+    class Config:
+        from_attributes = True
+
+
+class ApiKeyCreated(ApiKeyOut):
+    """Returned only once at creation — includes the raw key."""
+    raw_key: str = Field(..., description="The full API key — shown only this once.")
+
+
+class ApiKeyUpdate(BaseModel):
+    name:        Optional[str]      = Field(None, min_length=1, max_length=200)
+    description: Optional[str]      = None
+    scopes:      Optional[List[str]] = None
+    expires_at:  Optional[datetime]  = None
+    is_active:   Optional[bool]      = None
+
+    @field_validator("scopes")
+    @classmethod
+    def validate_scopes(cls, v: Optional[list]) -> Optional[list]:
+        if v is None:
+            return v
+        invalid = set(v) - VALID_SCOPES
+        if invalid:
+            raise ValueError(f"Invalid scopes: {invalid}")
+        return v