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/00016_init_payment_methods.sql

@@ -0,0 +1,23 @@
+-- +goose Up
+-- Create payment_methods table
+CREATE TABLE IF NOT EXISTS payment_methods (
+    id            TEXT PRIMARY KEY,
+    subscriber_id INTEGER NOT NULL,
+    gateway_id    TEXT,
+    type          TEXT NOT NULL,
+    customer_id   TEXT,
+    last4         TEXT,
+    brand         TEXT,
+    expiry_month  INTEGER,
+    expiry_year   INTEGER,
+    is_default    BOOLEAN NOT NULL DEFAULT false,
+    created_at    TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+-- Create indexes
+CREATE INDEX IF NOT EXISTS idx_payment_methods_subscriber_id ON payment_methods(subscriber_id);
+CREATE INDEX IF NOT EXISTS idx_payment_methods_gateway_id ON payment_methods(gateway_id);
+
+-- +goose Down
+-- Drop payment_methods table
+DROP TABLE IF EXISTS payment_methods CASCADE;