feat(notes): add_note MCP tool with a per-day agent cap

Agents can write into the user's daily notes, but only within limits:
max 10 agent notes a day, max 500 characters, add only — no edit, no
delete. A new from_agent column separates their lines from the user's
so the cap counts the right ones and the UI can mark them.

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

src/ClaudeDo.Data/Configuration/DailyNoteEntityConfiguration.cs

@@ -14,6 +14,7 @@ public class DailyNoteEntityConfiguration : IEntityTypeConfiguration<DailyNoteEn
         builder.Property(n => n.Date).HasColumnName("note_date").IsRequired();
         builder.Property(n => n.Text).HasColumnName("text").IsRequired();
         builder.Property(n => n.SortOrder).HasColumnName("sort_order").IsRequired();
+        builder.Property(n => n.FromAgent).HasColumnName("from_agent").IsRequired();
         builder.Property(n => n.CreatedAt).HasColumnName("created_at").IsRequired();
         builder.HasIndex(n => n.Date);
     }