feat: improve server management and refund display

Server Management:
- Fix /server command API auth (query param instead of header)
- Show server specs (vCPU/RAM/Bandwidth) in /server list
- Prevent AI from refusing server deletion based on expiration date
- Add explicit instructions in tool description and system prompt

Refund Display:
- Show before/after balance in server deletion refund message
- Format: 환불 전 잔액 → 환불 금액 → 환불 후 잔액

Other Changes:
- Add stopped status migration for server orders
- Clean up callback handler (remove deprecated code)
- Update constants and pattern utilities

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

migrations/005_add_stopped_status.sql

@@ -0,0 +1,62 @@
+-- Migration: Add 'stopped' status to server_orders table
+-- Date: 2026-01-29
+-- Description: SQLite does not support ALTER TABLE to modify CHECK constraints,
+--              so we need to recreate the table with the new constraint.
+
+-- Step 1: Create temporary table with new CHECK constraint
+CREATE TABLE server_orders_new (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  user_id INTEGER NOT NULL,
+  spec_id INTEGER NOT NULL,
+  status TEXT NOT NULL DEFAULT 'pending' CHECK(status IN ('pending', 'provisioning', 'active', 'stopped', 'failed', 'cancelled', 'terminated')),
+  region TEXT NOT NULL,
+  provider_instance_id TEXT,
+  ip_address TEXT,
+  root_password TEXT,
+  price_paid INTEGER NOT NULL,
+  error_message TEXT,
+  provisioned_at DATETIME,
+  terminated_at DATETIME,
+  created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+  updated_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+  label TEXT,
+  image TEXT,
+  billing_type TEXT DEFAULT 'monthly',
+  expires_at DATETIME,
+  telegram_user_id TEXT,
+  provider TEXT DEFAULT 'anvil',
+  idempotency_key TEXT,
+  FOREIGN KEY (user_id) REFERENCES users(id)
+);
+
+-- Step 2: Copy existing data
+INSERT INTO server_orders_new (
+  id, user_id, spec_id, status, region, provider_instance_id, ip_address,
+  root_password, price_paid, error_message, provisioned_at, terminated_at,
+  created_at, updated_at, label, image, billing_type, expires_at,
+  telegram_user_id, provider, idempotency_key
+)
+SELECT
+  id, user_id, spec_id, status, region, provider_instance_id, ip_address,
+  root_password, price_paid, error_message, provisioned_at, terminated_at,
+  created_at, updated_at, label, image, billing_type, expires_at,
+  telegram_user_id, provider, idempotency_key
+FROM server_orders;
+
+-- Step 3: Drop old table
+DROP TABLE server_orders;
+
+-- Step 4: Rename new table
+ALTER TABLE server_orders_new RENAME TO server_orders;
+
+-- Step 5: Recreate indexes
+CREATE INDEX idx_server_orders_user ON server_orders(user_id);
+
+CREATE INDEX idx_server_orders_status ON server_orders(status, created_at DESC);
+
+CREATE UNIQUE INDEX idx_server_orders_idempotency_unique
+  ON server_orders(idempotency_key)
+  WHERE idempotency_key IS NOT NULL;
+
+-- Verification query (comment out for actual migration)
+-- SELECT COUNT(*) as total_orders, COUNT(DISTINCT status) as status_count FROM server_orders;

migrations/005_rollback_stopped_status.sql

@@ -0,0 +1,67 @@
+-- Rollback Migration: Remove 'stopped' status from server_orders table
+-- Date: 2026-01-29
+-- Description: Revert to original CHECK constraint without 'stopped' status
+-- WARNING: This will fail if there are any rows with status='stopped'
+
+-- Step 1: Verify no 'stopped' status exists (will fail if found)
+-- If this SELECT returns rows, manual intervention required
+SELECT CASE
+  WHEN COUNT(*) > 0 THEN RAISE(ABORT, 'Cannot rollback: server_orders contains stopped status records')
+  ELSE 0
+END
+FROM server_orders WHERE status = 'stopped';
+
+-- Step 2: Create temporary table with original CHECK constraint
+CREATE TABLE server_orders_rollback (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  user_id INTEGER NOT NULL,
+  spec_id INTEGER NOT NULL,
+  status TEXT NOT NULL DEFAULT 'pending' CHECK(status IN ('pending', 'provisioning', 'active', 'failed', 'cancelled', 'terminated')),
+  region TEXT NOT NULL,
+  provider_instance_id TEXT,
+  ip_address TEXT,
+  root_password TEXT,
+  price_paid INTEGER NOT NULL,
+  error_message TEXT,
+  provisioned_at DATETIME,
+  terminated_at DATETIME,
+  created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+  updated_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+  label TEXT,
+  image TEXT,
+  billing_type TEXT DEFAULT 'monthly',
+  expires_at DATETIME,
+  telegram_user_id TEXT,
+  provider TEXT DEFAULT 'anvil',
+  idempotency_key TEXT,
+  FOREIGN KEY (user_id) REFERENCES users(id)
+);
+
+-- Step 3: Copy existing data
+INSERT INTO server_orders_rollback (
+  id, user_id, spec_id, status, region, provider_instance_id, ip_address,
+  root_password, price_paid, error_message, provisioned_at, terminated_at,
+  created_at, updated_at, label, image, billing_type, expires_at,
+  telegram_user_id, provider, idempotency_key
+)
+SELECT
+  id, user_id, spec_id, status, region, provider_instance_id, ip_address,
+  root_password, price_paid, error_message, provisioned_at, terminated_at,
+  created_at, updated_at, label, image, billing_type, expires_at,
+  telegram_user_id, provider, idempotency_key
+FROM server_orders;
+
+-- Step 4: Drop current table
+DROP TABLE server_orders;
+
+-- Step 5: Rename rollback table
+ALTER TABLE server_orders_rollback RENAME TO server_orders;
+
+-- Step 6: Recreate indexes
+CREATE INDEX idx_server_orders_user ON server_orders(user_id);
+
+CREATE INDEX idx_server_orders_status ON server_orders(status, created_at DESC);
+
+CREATE UNIQUE INDEX idx_server_orders_idempotency_unique
+  ON server_orders(idempotency_key)
+  WHERE idempotency_key IS NOT NULL;