Add `kind` field to DMO MCP content schemas (dailyTask vs challenge)

## Problem The SAGA API supports a `kind` field on DMO challenge entries (`dailyTask` | `challenge`), but this field is absent from the MCP tool schemas for `patch_dmo_content` and `get_dmo_content`. This means: - Agents cannot set `kind` when creating challenges via MCP (the field is silently accepted by the API but undocumented) - `get_dmo_content` responses do not surface `kind`, so agents cannot distinguish DMO daily tasks from one-time challenge catalog entries - Agents have no way to know that `resetAfter: 0` is the correct pattern for challenges vs `resetAfter: 1` for daily tasks ## Current workaround Passing `kind: "challenge"` directly in the patch payload does reach the API and is persisted, but this relies on undocumented behaviour and schema pass-through. ## Requested changes 1. Add `kind` as an explicit enum field (`"dailyTask" | "challenge"`) to the `patch_dmo_content` input schema 2. Include `kind` in `get_dmo_content` response output so agents can read and preserve it 3. Update the step description hint to clarify that challenge-kind entries should use `resetAfter: 0` while dailyTask entries use `resetAfter: 1` ## Why it matters Without this, AI agents creating non-resetting programs (ambassador homework, onboarding checklists) cannot reliably target the Challenges section vs the DMO section, and the distinction is invisible in API responses.