BE-CAL-API-005: implement plan-schedule / plan-list API

- Add SchedulePlanCreate, SchedulePlanResponse, SchedulePlanListResponse schemas
- Add DayOfWeekEnum, MonthOfYearEnum schema enums
- Add POST /calendar/plans endpoint (create plan with hierarchy validation)
- Add GET /calendar/plans endpoint (list plans, optional include_inactive)
- Add GET /calendar/plans/{plan_id} endpoint (get single plan)

app/schemas/calendar.py

@@ -251,3 +251,89 @@ class TimeSlotCancelResponse(BaseModel):
     """Response after cancelling a slot — includes the cancelled slot."""
     slot: TimeSlotResponse
     message: str = Field("Slot cancelled successfully", description="Human-readable result")
+
+
+# ---------------------------------------------------------------------------
+# SchedulePlan enums (mirror DB enums)
+# ---------------------------------------------------------------------------
+
+class DayOfWeekEnum(str, Enum):
+    SUN = "sun"
+    MON = "mon"
+    TUE = "tue"
+    WED = "wed"
+    THU = "thu"
+    FRI = "fri"
+    SAT = "sat"
+
+
+class MonthOfYearEnum(str, Enum):
+    JAN = "jan"
+    FEB = "feb"
+    MAR = "mar"
+    APR = "apr"
+    MAY = "may"
+    JUN = "jun"
+    JUL = "jul"
+    AUG = "aug"
+    SEP = "sep"
+    OCT = "oct"
+    NOV = "nov"
+    DEC = "dec"
+
+
+# ---------------------------------------------------------------------------
+# SchedulePlan create / response (BE-CAL-API-005)
+# ---------------------------------------------------------------------------
+
+class SchedulePlanCreate(BaseModel):
+    """Request body for creating a recurring schedule plan."""
+    slot_type: SlotTypeEnum = Field(..., description="work | on_call | entertainment | system")
+    estimated_duration: int = Field(..., ge=1, le=50, description="Duration in minutes (1-50)")
+    at_time: time = Field(..., description="Daily scheduled time (HH:MM)")
+    on_day: Optional[DayOfWeekEnum] = Field(None, description="Day of week (sun-sat)")
+    on_week: Optional[int] = Field(None, ge=1, le=4, description="Week of month (1-4)")
+    on_month: Optional[MonthOfYearEnum] = Field(None, description="Month (jan-dec)")
+    event_type: Optional[EventTypeEnum] = Field(None, description="job | entertainment | system_event")
+    event_data: Optional[dict[str, Any]] = Field(None, description="Event details JSON")
+
+    @field_validator("at_time")
+    @classmethod
+    def _validate_at_time(cls, v: time) -> time:
+        if v.hour > 23:
+            raise ValueError("at_time hour must be between 00 and 23")
+        return v
+
+    @model_validator(mode="after")
+    def _validate_hierarchy(self) -> "SchedulePlanCreate":
+        """Enforce period-parameter hierarchy: on_month → on_week → on_day."""
+        if self.on_month is not None and self.on_week is None:
+            raise ValueError("on_month requires on_week to be set")
+        if self.on_week is not None and self.on_day is None:
+            raise ValueError("on_week requires on_day to be set")
+        return self
+
+
+class SchedulePlanResponse(BaseModel):
+    """Response for a single SchedulePlan."""
+    id: int
+    user_id: int
+    slot_type: str
+    estimated_duration: int
+    at_time: str  # HH:MM:SS ISO format
+    on_day: Optional[str] = None
+    on_week: Optional[int] = None
+    on_month: Optional[str] = None
+    event_type: Optional[str] = None
+    event_data: Optional[dict[str, Any]] = None
+    is_active: bool
+    created_at: Optional[datetime] = None
+    updated_at: Optional[datetime] = None
+
+    class Config:
+        from_attributes = True
+
+
+class SchedulePlanListResponse(BaseModel):
+    """Response for listing schedule plans."""
+    plans: list[SchedulePlanResponse] = Field(default_factory=list)