feat: Secrets

[Ark-kun]

API changes

List secrets: GET /api/secrets/.
Create a secret: POST /api/secrets/.
Update a secret: PUT /api/secrets/{secret_name}.
Delete a secret: DELETE /api/secrets/{secret_name}.

DB changes

class Secret(_TableBase):
    __tablename__ = "secret"
    user_id: orm.Mapped[str] = orm.mapped_column(primary_key=True, index=True)
    secret_name: orm.Mapped[str] = orm.mapped_column(primary_key=True)
    secret_value: orm.Mapped[str]
    created_at: orm.Mapped[datetime.datetime | None] = orm.mapped_column(default=None)
    updated_at: orm.Mapped[datetime.datetime | None] = orm.mapped_column(default=None)
    extra_data: orm.Mapped[dict[str, Any] | None] = orm.mapped_column(default=None)

TaskSpec changes

componentRef: ...
  spec:
    inputs:
    - {name: input4, type: Secret}
arguments:
  input1: "constant value"
  input2:
    taskOutput:
      taskId: "task1"
      outputName: "output1"
  input3:
    graphInput:
      inputName: "graph_input_1"
  # New:
  input4:
    dynamicData:
      secret:
        name: "API_TOKEN"

Fixes: #51

[yuechao-qin]

Some questions/comments. Great work getting secrets working quickly!

[yuechao-qin]

The only major issue out of my comments would be ItemAlreadyExistsError exception handler. Others are enhancements/suggestions.