feat: Add comprehensive database schema migrations for all platform tables

- Add subscribers table with IMSI, MSISDN, authentication keys, and eSIM profile fields
- Add service_plans table for data/voice/SMS limits and QoS parameters (ARPA, AMBR)
- Add sessions table for tracking PDU sessions with QoS and usage metrics
- Add usage_records table for billing and charging data
- Add users table with role-based access control fields
- Add roles, permissions, and role_permissions junction table for RBAC
- Add auth

migrations/00006_init_usage_records.sql

@@ -0,0 +1,27 @@
+-- +goose Up
+-- Create usage_records table
+CREATE TABLE IF NOT EXISTS usage_records (
+    id           SERIAL PRIMARY KEY,
+    subscriber_id INTEGER NOT NULL,
+    session_id   INTEGER,
+    usage_type   TEXT NOT NULL,
+    start_time   TIMESTAMPTZ NOT NULL,
+    end_time     TIMESTAMPTZ NOT NULL,
+    volume       BIGINT NOT NULL,
+    rate         DOUBLE PRECISION,
+    cost         DOUBLE PRECISION,
+    billing_cycle TEXT,
+    invoice_id   INTEGER,
+    created_at   TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    updated_at   TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+-- Create indexes
+CREATE INDEX IF NOT EXISTS idx_usage_records_subscriber_id ON usage_records(subscriber_id);
+CREATE INDEX IF NOT EXISTS idx_usage_records_session_id ON usage_records(session_id);
+CREATE INDEX IF NOT EXISTS idx_usage_records_usage_type ON usage_records(usage_type);
+CREATE INDEX IF NOT EXISTS idx_usage_records_billing_cycle ON usage_records(billing_cycle);
+
+-- +goose Down
+-- Drop usage_records table
+DROP TABLE IF EXISTS usage_records CASCADE;