refactor: Rename SCHEMA_SQL to INITIAL_SCHEMA_SQL

This aligns with ADR-033's migration system redesign. The initial schema
represents the v1.0.0 baseline and should not be modified. All schema
changes after v1.0.0 must go in migration files.

Changes:
- Renamed SCHEMA_SQL → INITIAL_SCHEMA_SQL in database.py
- Updated all references in migrations.py comments
- Added comment: "DO NOT MODIFY - This represents the v1.0.0 schema state"
- No functional changes, purely documentation improvement

Part of v1.1.0 migration system redesign (Phase 2).

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

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

starpunk/database.py

@@ -7,8 +7,10 @@ import sqlite3
 from pathlib import Path
 
 
-# Database schema
-SCHEMA_SQL = """
+# Initial database schema (v1.0.0 baseline)
+# DO NOT MODIFY - This represents the v1.0.0 schema state
+# All schema changes after v1.0.0 must go in migration files
+INITIAL_SCHEMA_SQL = """
 -- Notes metadata (content is in files)
 CREATE TABLE IF NOT EXISTS notes (
     id INTEGER PRIMARY KEY AUTOINCREMENT,
@@ -107,7 +109,7 @@ def init_db(app=None):
     # Create database and initial schema
     conn = sqlite3.connect(db_path)
     try:
-        conn.executescript(SCHEMA_SQL)
+        conn.executescript(INITIAL_SCHEMA_SQL)
         conn.commit()
         if logger:
             logger.info(f"Database initialized: {db_path}")