feat: add address source tracking (source_meta field) (#794)

- Add source_meta field to address table for tracking creation source
- Web: records client IP address (with fallback to 'web:unknown')
- Telegram: records 'tg:{userId}'
- Admin: records 'admin'
- Add database migration with field existence check
- Add frontend display in admin Account page
- Backward compatible: fallback if field doesn't exist

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-authored-by: Claude <noreply@anthropic.com>

db/schema.sql

@@ -18,6 +18,7 @@ CREATE TABLE IF NOT EXISTS address (
     id INTEGER PRIMARY KEY AUTOINCREMENT,
     name TEXT UNIQUE,
     password TEXT,
+    source_meta TEXT,
     created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
     updated_at DATETIME DEFAULT CURRENT_TIMESTAMP
 );
@@ -28,6 +29,8 @@ CREATE INDEX IF NOT EXISTS idx_address_created_at ON address(created_at);
 
 CREATE INDEX IF NOT EXISTS idx_address_updated_at ON address(updated_at);
 
+CREATE INDEX IF NOT EXISTS idx_address_source_meta ON address(source_meta);
+
 CREATE TABLE IF NOT EXISTS auto_reply_mails (
     id INTEGER PRIMARY KEY,
     source_prefix TEXT,