feat(backend): Add Syndarix domain models with CRUD operations

- Add Project model with slug, description, autonomy level, and settings
- Add AgentType model for agent templates with model config and failover
- Add AgentInstance model for running agents with status and memory
- Add Issue model with external tracker sync (Gitea/GitHub/GitLab)
- Add Sprint model with velocity tracking and lifecycle management
- Add comprehensive Pydantic schemas with validation
- Add full CRUD operations for all models with filtering/sorting
- Add 280+ tests for models, schemas, and CRUD operations

Implements #23, #24, #25, #26, #27

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

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

backend/app/schemas/syndarix/__init__.py

@@ -0,0 +1,113 @@
+# app/schemas/syndarix/__init__.py
+"""
+Syndarix domain schemas.
+
+This package contains Pydantic schemas for validating and serializing
+Syndarix domain entities.
+"""
+
+from .agent_instance import (
+    AgentInstanceCreate,
+    AgentInstanceInDB,
+    AgentInstanceListResponse,
+    AgentInstanceMetrics,
+    AgentInstanceResponse,
+    AgentInstanceTerminate,
+    AgentInstanceUpdate,
+)
+from .agent_type import (
+    AgentTypeCreate,
+    AgentTypeInDB,
+    AgentTypeListResponse,
+    AgentTypeResponse,
+    AgentTypeUpdate,
+)
+from .enums import (
+    AgentStatus,
+    AutonomyLevel,
+    IssuePriority,
+    IssueStatus,
+    ProjectStatus,
+    SprintStatus,
+    SyncStatus,
+)
+from .issue import (
+    IssueAssign,
+    IssueClose,
+    IssueCreate,
+    IssueInDB,
+    IssueListResponse,
+    IssueResponse,
+    IssueStats,
+    IssueSyncUpdate,
+    IssueUpdate,
+)
+from .project import (
+    ProjectCreate,
+    ProjectInDB,
+    ProjectListResponse,
+    ProjectResponse,
+    ProjectUpdate,
+)
+from .sprint import (
+    SprintBurndown,
+    SprintComplete,
+    SprintCreate,
+    SprintInDB,
+    SprintListResponse,
+    SprintResponse,
+    SprintStart,
+    SprintUpdate,
+    SprintVelocity,
+)
+
+__all__ = [
+    # AgentInstance schemas
+    "AgentInstanceCreate",
+    "AgentInstanceInDB",
+    "AgentInstanceListResponse",
+    "AgentInstanceMetrics",
+    "AgentInstanceResponse",
+    "AgentInstanceTerminate",
+    "AgentInstanceUpdate",
+    # Enums
+    "AgentStatus",
+    # AgentType schemas
+    "AgentTypeCreate",
+    "AgentTypeInDB",
+    "AgentTypeListResponse",
+    "AgentTypeResponse",
+    "AgentTypeUpdate",
+    "AutonomyLevel",
+    # Issue schemas
+    "IssueAssign",
+    "IssueClose",
+    "IssueCreate",
+    "IssueInDB",
+    "IssueListResponse",
+    "IssuePriority",
+    "IssueResponse",
+    "IssueStats",
+    "IssueStatus",
+    "IssueSyncUpdate",
+    "IssueUpdate",
+    # Project schemas
+    "ProjectCreate",
+    "ProjectInDB",
+    "ProjectListResponse",
+    "ProjectResponse",
+    "ProjectStatus",
+    "ProjectUpdate",
+    # Sprint schemas
+    "SprintBurndown",
+    "SprintComplete",
+    "SprintCreate",
+    "SprintInDB",
+    "SprintListResponse",
+    "SprintResponse",
+    "SprintStart",
+    "SprintStatus",
+    "SprintUpdate",
+    "SprintVelocity",
+    "SyncStatus",
+]