Restructured project

- backend moved to backend directory
- added and initialized frontend with vue
- moved infrastructure files to infra directory

backend/migrations/000004_create_family_threads.up.sql

@@ -0,0 +1,19 @@
+CREATE TABLE  family_threads
+(
+    id                BIGSERIAL PRIMARY KEY,
+    family_id         BIGINT    NOT NULL REFERENCES families (id) ON DELETE CASCADE,
+    type              TEXT      NOT NULL,
+    title             TEXT      NOT NULL,
+    telegram_topic_id BIGINT    NOT NULL,
+    is_system         BOOLEAN   NOT NULL DEFAULT FALSE,
+    created_by        BIGINT    NOT NULL REFERENCES users (id),
+    created_at        TIMESTAMP NOT NULL DEFAULT NOW(),
+
+    UNIQUE (family_id, telegram_topic_id)
+);
+
+CREATE UNIQUE INDEX idx_unique_system_threads ON family_threads (family_id, type) WHERE is_system = TRUE;
+
+CREATE INDEX idx_threads_family_id ON family_threads (family_id);
+
+CREATE INDEX idx_threads_family_type ON family_threads (family_id, type);