add birthday_calendar table migrations

crates/store_sqlite/migrations/20251102192200_birthday_calendars.down.sql

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+DROP TABLE birthday_calendars;

crates/store_sqlite/migrations/20251102192200_birthday_calendars.up.sql

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+CREATE TABLE birthday_calendars (
+    principal TEXT NOT NULL,
+    id TEXT NOT NULL,
+    displayname TEXT,
+    description TEXT,
+    "order" INT DEFAULT 0 NOT NULL,
+    color TEXT,
+    timezone_id TEXT,
+    deleted_at DATETIME,
+    push_topic TEXT NOT NULL,
+    PRIMARY KEY (principal, id),
+    CONSTRAINT fk_birthdays_addressbooks FOREIGN KEY (principal, id)
+    REFERENCES addressbooks (principal, id) ON DELETE CASCADE
+    -- birthday calendar stores no meaningful data so we can cascade
+)