Let a household choose to be paid for the red days

Asking for a full week off never spent anything on the Saturday, the
Sunday or a holiday, and a test now says so outright rather than leaving
it to be rediscovered. Those days are free because vacation cannot be
taken on a day that is not a working day.

Parental benefit is a payment rather than a schedule, though, so it can
be drawn on a red day to turn an unpaid day off into a paid one — at the
cost of a day the family would otherwise keep. That is now a workspace
setting, off by default, and it never reaches for a vacation day. With it
off the planner behaves exactly as before.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Ei7gCZzdd751uZtPzb1Pep

backend/app/models/workspace.py

@@ -15,12 +15,17 @@ class WorkspaceCreate(BaseModel):
 
 class WorkspaceUpdate(BaseModel):
     name: str | None = Field(default=None, min_length=1, max_length=100)
+    # §todo item 2 — `None` means "leave unchanged"; only an explicit
+    # true/false updates the stored flag (mirrors `name`'s omit-to-keep
+    # convention above).
+    take_pl_on_red_days: bool | None = None
 
 
 class WorkspaceResponse(BaseModel):
     id: UUID
     name: str
     created_at: datetime | None
+    take_pl_on_red_days: bool
 
     @classmethod
     def from_entity(cls, ws: Workspace) -> "WorkspaceResponse":
@@ -28,6 +33,7 @@ class WorkspaceResponse(BaseModel):
             id=ws.id,
             name=ws.name,
             created_at=ws.created_at,
+            take_pl_on_red_days=ws.take_pl_on_red_days,
         )