fix(db): correct SQL comment syntax for SQLite compatibility

- Replace Python-style # comments with SQL-standard -- comments
- SQLite does not recognize # as comment character
- Fixes database initialization failure on first run

Test: Database now initializes successfully.

core/schema.sql

@@ -1,7 +1,7 @@
-# Description: SQLite database schema for Lemontropia Suite
-# Implements the Data Principle: Every session is a Project
-# Schema version: 1.0.0
-# Created: 2026-02-08
+-- Description: SQLite database schema for Lemontropia Suite
+-- Implements the Data Principle: Every session is a Project
+-- Schema version: 1.0.0
+-- Created: 2026-02-08
 
 -- Enable foreign key support
 PRAGMA foreign_keys = ON;