Harden secrets handling: env-var DB password + defensive .gitignore

Move hardcoded 'rootpassword' default in parser/{config,backfill_changeover,
clmparser,udcparser}.py behind os.environ.get('SHOPDB_DB_PASSWORD',
'rootpassword'). Add defensive patterns (.env, *.key, *.pem, id_rsa*,
secrets.*, etc.) to .gitignore across all project repos.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.gitignore

@@ -18,3 +18,22 @@ ENV/
 # OS
 .DS_Store
 Thumbs.db
+
+# Secrets and credentials (defensive)
+.env
+.env.*
+!.env.example
+!.env.*.example
+*.pem
+*.key
+id_rsa
+id_rsa.*
+*.ppk
+*.p12
+*.pfx
+secrets.json
+secrets.yaml
+secrets.yml
+*_secret
+*_secrets
+credentials.json