Add package dependencies and project settings page

Package Dependencies:
- Add artifact dependency management system
- Add dependency API endpoints (get, resolve, reverse)
- Add ensure file parsing for declaring dependencies
- Add circular dependency and conflict detection
- Add frontend dependency visualization with graph modal
- Add migration for artifact_dependencies table

Project Settings Page (#65):
- Add dedicated settings page for project admins
- General settings section (description, visibility)
- Access management section (moved from project page)
- Danger zone with inline delete confirmation
- Add Settings button to project page header

backend/app/schemas.py

@@ -916,3 +916,140 @@ class ProjectWithAccessResponse(ProjectResponse):
     """Project response with user's access level"""
     user_access_level: Optional[str] = None
 
+
+# Artifact Dependency schemas
+class DependencyCreate(BaseModel):
+    """Schema for creating a dependency"""
+    project: str
+    package: str
+    version: Optional[str] = None
+    tag: Optional[str] = None
+
+    @field_validator('version', 'tag')
+    @classmethod
+    def validate_constraint(cls, v, info):
+        return v
+
+    def model_post_init(self, __context):
+        """Validate that exactly one of version or tag is set"""
+        if self.version is None and self.tag is None:
+            raise ValueError("Either 'version' or 'tag' must be specified")
+        if self.version is not None and self.tag is not None:
+            raise ValueError("Cannot specify both 'version' and 'tag'")
+
+
+class DependencyResponse(BaseModel):
+    """Schema for dependency response"""
+    id: UUID
+    artifact_id: str
+    project: str
+    package: str
+    version: Optional[str] = None
+    tag: Optional[str] = None
+    created_at: datetime
+
+    class Config:
+        from_attributes = True
+
+    @classmethod
+    def from_orm_model(cls, dep) -> "DependencyResponse":
+        """Create from ORM model with field mapping"""
+        return cls(
+            id=dep.id,
+            artifact_id=dep.artifact_id,
+            project=dep.dependency_project,
+            package=dep.dependency_package,
+            version=dep.version_constraint,
+            tag=dep.tag_constraint,
+            created_at=dep.created_at,
+        )
+
+
+class ArtifactDependenciesResponse(BaseModel):
+    """Response containing all dependencies for an artifact"""
+    artifact_id: str
+    dependencies: List[DependencyResponse]
+
+
+class DependentInfo(BaseModel):
+    """Information about an artifact that depends on a package"""
+    artifact_id: str
+    project: str
+    package: str
+    version: Optional[str] = None
+    constraint_type: str  # 'version' or 'tag'
+    constraint_value: str
+
+
+class ReverseDependenciesResponse(BaseModel):
+    """Response containing packages that depend on a given package"""
+    project: str
+    package: str
+    dependents: List[DependentInfo]
+    pagination: PaginationMeta
+
+
+class EnsureFileDependency(BaseModel):
+    """Dependency entry from orchard.ensure file"""
+    project: str
+    package: str
+    version: Optional[str] = None
+    tag: Optional[str] = None
+
+    @field_validator('version', 'tag')
+    @classmethod
+    def validate_constraint(cls, v, info):
+        return v
+
+    def model_post_init(self, __context):
+        """Validate that exactly one of version or tag is set"""
+        if self.version is None and self.tag is None:
+            raise ValueError("Either 'version' or 'tag' must be specified")
+        if self.version is not None and self.tag is not None:
+            raise ValueError("Cannot specify both 'version' and 'tag'")
+
+
+class EnsureFileContent(BaseModel):
+    """Parsed content of orchard.ensure file"""
+    dependencies: List[EnsureFileDependency] = []
+
+
+class ResolvedArtifact(BaseModel):
+    """A resolved artifact in the dependency tree"""
+    artifact_id: str
+    project: str
+    package: str
+    version: Optional[str] = None
+    tag: Optional[str] = None
+    size: int
+    download_url: str
+
+
+class DependencyResolutionResponse(BaseModel):
+    """Response from dependency resolution endpoint"""
+    requested: Dict[str, str]  # project, package, ref
+    resolved: List[ResolvedArtifact]
+    total_size: int
+    artifact_count: int
+
+
+class DependencyConflict(BaseModel):
+    """Details about a dependency conflict"""
+    project: str
+    package: str
+    requirements: List[Dict[str, Any]]  # version/tag and required_by info
+
+
+class DependencyConflictError(BaseModel):
+    """Error response for dependency conflicts"""
+    error: str = "dependency_conflict"
+    message: str
+    conflicts: List[DependencyConflict]
+
+
+class CircularDependencyError(BaseModel):
+    """Error response for circular dependencies"""
+    error: str = "circular_dependency"
+    message: str
+    cycle: List[str]  # List of "project/package" strings showing the cycle
+