Add room size setting, constraint management with grouped color-coded tags

schema.sql

@@ -1,5 +1,8 @@
+DROP TABLE IF EXISTS roommate_constraints;
+DROP TYPE IF EXISTS constraint_kind;
+
 DO $$ BEGIN
-    CREATE TYPE constraint_kind AS ENUM ('happy', 'ok', 'never');
+    CREATE TYPE constraint_kind AS ENUM ('must', 'prefer', 'prefer_not', 'must_not');
 EXCEPTION WHEN duplicate_object THEN NULL;
 END $$;
 
@@ -13,6 +16,8 @@ CREATE TABLE IF NOT EXISTS trips (
     name TEXT NOT NULL
 );
 
+ALTER TABLE trips ADD COLUMN IF NOT EXISTS room_size INTEGER NOT NULL DEFAULT 2;
+
 CREATE TABLE IF NOT EXISTS trip_admins (
     id BIGSERIAL PRIMARY KEY,
     trip_id BIGINT NOT NULL REFERENCES trips(id) ON DELETE CASCADE,
@@ -41,5 +46,6 @@ CREATE TABLE IF NOT EXISTS roommate_constraints (
     student_b_id BIGINT NOT NULL REFERENCES students(id) ON DELETE CASCADE,
     kind constraint_kind NOT NULL,
     level constraint_level NOT NULL,
+    CHECK(student_a_id < student_b_id),
     UNIQUE(student_a_id, student_b_id, level)
 );