fix: rename 000_bootstrap.sql to 000.sql per issue spec

Move the inline CREATE TABLE IF NOT EXISTS schema_migrations from Go
code into a dedicated 000_bootstrap.sql file, following the sneak/pixa
pattern. The bootstrap SQL is executed directly before the migration
loop, which now starts from 001+. The bootstrap file also handles its
own INSERT OR IGNORE so the Go code does zero inserts for version 0.

closes #91

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

internal/db/db.go

@@ -135,13 +135,21 @@ type migration struct {
 func (database *Database) runMigrations(
 	ctx context.Context,
 ) error {
-	_, err := database.conn.ExecContext(ctx,
-		`CREATE TABLE IF NOT EXISTS schema_migrations (
-		 version INTEGER PRIMARY KEY,
-		 applied_at DATETIME DEFAULT CURRENT_TIMESTAMP)`)
+	bootstrap, err := SchemaFiles.ReadFile(
+		"schema/000.sql",
+	)
 	if err != nil {
 		return fmt.Errorf(
-			"create schema_migrations: %w", err,
+			"read bootstrap migration: %w", err,
+		)
+	}
+
+	_, err = database.conn.ExecContext(
+		ctx, string(bootstrap),
+	)
+	if err != nil {
+		return fmt.Errorf(
+			"execute bootstrap migration: %w", err,
 		)
 	}
 
@@ -270,6 +278,11 @@ func (database *Database) loadMigrations() (
 			continue
 		}
 
+		// Skip bootstrap migration; it is executed separately.
+		if version == 0 {
+			continue
+		}
+
 		content, readErr := SchemaFiles.ReadFile(
 			"schema/" + entry.Name(),
 		)

internal/db/schema/000.sql

@@ -0,0 +1,6 @@
+-- Bootstrap: create the schema_migrations table itself.
+CREATE TABLE IF NOT EXISTS schema_migrations (
+    version INTEGER PRIMARY KEY,
+    applied_at DATETIME DEFAULT CURRENT_TIMESTAMP
+);
+INSERT OR IGNORE INTO schema_migrations (version) VALUES (0);