Database refactor and test coverage

backend/internal/database/migrations/0020_projects.sql

@@ -1,11 +1,9 @@
 CREATE TABLE IF NOT EXISTS projects (
   id INTEGER PRIMARY KEY,
-  projectId TEXT DEFAULT (HEX(RANDOMBLOB(4))) NOT NULL UNIQUE,
   name VARCHAR(255) NOT NULL UNIQUE,
   description TEXT NOT NULL,
   owner_user_id INTEGER NOT NULL,
   FOREIGN KEY (owner_user_id) REFERENCES users (id)
 );
 
-CREATE INDEX IF NOT EXISTS projects_projectId_index ON projects (projectId);
 CREATE INDEX IF NOT EXISTS projects_user_id_index ON projects (owner_user_id);

backend/internal/database/migrations/0030_time_reports.sql

@@ -1,10 +1,11 @@
 CREATE TABLE IF NOT EXISTS time_reports (
   id INTEGER PRIMARY KEY,
-  reportId TEXT DEFAULT (HEX(RANDOMBLOB(6))) NOT NULL UNIQUE,
   project_id INTEGER NOT NULL,
+  user_id INTEGER NOT NULL,
   start DATETIME NOT NULL,
   end DATETIME NOT NULL,
   FOREIGN KEY (project_id) REFERENCES projects (id) ON DELETE CASCADE
+  FOREIGN KEY (user_id) REFERENCES users (id) ON DELETE CASCADE
 );
 
 CREATE TRIGGER IF NOT EXISTS time_reports_start_before_end