Add event colors (Catppuccin Mocha) and read-only week view for users

Admins can now pick a color per event from a Catppuccin Mocha palette;
existing events default to blue. Colors flow through to both the admin
timeline and the new "Неделя" tab in the user view, which reuses the
admin's weekly grid in a read-only mode. Also reworks event blocks to
show a single-line "start–end title" so short events no longer overflow,
tidies the admin toolbar, and expands mobile responsiveness across both
frontends.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

backend/models.py

@@ -12,6 +12,7 @@ class EventCreate(BaseModel):
     duration_min: int
     title: str
     repeat_weekly: bool = False
+    color: str = "blue"  # ключ цвета из палитры Catppuccin Mocha
 
 class TaskResponse(BaseModel):
     id: int
@@ -28,6 +29,7 @@ class EventResponse(BaseModel):
     title: str
     kind: Literal["event"] = "event"
     repeat_weekly: bool = False
+    color: str = "blue"
 
 class ScheduleItem(BaseModel):
     kind: Literal["task", "event"]
@@ -38,6 +40,7 @@ class ScheduleItem(BaseModel):
     start_time: Optional[str] = None
     duration_min: Optional[int] = None
     repeat_weekly: Optional[bool] = None
+    color: Optional[str] = None
 
 class ScheduleResponse(BaseModel):
     items: list[ScheduleItem]
@@ -49,3 +52,4 @@ class UpdateRequest(BaseModel):
     duration_min: Optional[int] = None
     occurrence_date: Optional[str] = None
     scope: Optional[Literal["one_date", "series"]] = None  # для weekly tasks
+    color: Optional[str] = None