fix(todo): describe the MCP priority the way the app reads it (#2297)

The create_todo and update_todo tools said 1 was low and 3 was high. The
app, its sort and the wiki all say the opposite: 1 is P1, the red one at the
top of the list. An assistant that followed the description filed every
urgent task as the least urgent. The words now match the badges, and the
update tool, which said nothing at all, says the same and that null clears
it. No stored value changes.

server/src/nest/todo/todo.mcp.ts

@@ -65,7 +65,7 @@ export class TodoMcp {
       due_date: z.string().regex(/^\d{4}-\d{2}-\d{2}$/).optional().describe('Due date (YYYY-MM-DD)'),
       description: z.string().max(2000).optional().describe('Additional description'),
       assigned_user_id: z.number().int().positive().optional().describe('User ID to assign this task to'),
-      priority: z.number().int().min(0).max(3).optional().describe('Priority: 0=none, 1=low, 2=medium, 3=high'),
+      priority: z.number().int().min(0).max(3).optional().describe('Priority: 0=none, 1=P1 (highest), 2=P2, 3=P3 (lowest)'),
     },
     annotations: TOOL_ANNOTATIONS_NON_IDEMPOTENT,
     when: packingAddonOn,
@@ -96,7 +96,7 @@ export class TodoMcp {
       due_date: z.string().regex(/^\d{4}-\d{2}-\d{2}$/).nullable().optional().describe('Set to null to clear the due date'),
       description: z.string().max(2000).nullable().optional().describe('Set to null to clear'),
       assigned_user_id: z.number().int().positive().nullable().optional().describe('Set to null to unassign'),
-      priority: z.number().int().min(0).max(3).nullable().optional(),
+      priority: z.number().int().min(0).max(3).nullable().optional().describe('Priority: 0=none, 1=P1 (highest), 2=P2, 3=P3 (lowest); null clears it'),
     },
     annotations: TOOL_ANNOTATIONS_WRITE,
     when: packingAddonOn,