Deprecate --store-compliance on extension validate #1407

TODO

Deprecate --store-compliance on extension validate. Use the config key instead:

validation:
  store_compliance: true

Today three switches set the same field: the flag, SHOPWARE_CLI_STORE_COMPLIANCE=1, and the YAML key. It only gates validateAssets (source vs compiled asset pairing). The flag's "wipe validation.ignore" is broken anyway: the ignores are copied to toolCfg.ValidationIgnores before the wipe. So the flag just duplicates the YAML key.

Work

1. Mark the flag deprecated and point to validation.store_compliance
2. Env var: keep it as an override and document it, or deprecate it along with the flag (drop the os.Getenv branch in cmd/extension/extension_validate.go)
3. Changelog and flag help text
4. Remove the flag after the deprecation window; keep the config field and the gate

Keep the flag working until then so CI doesn't break.

Out of scope

• New store-compliance checks (Add an Agent Skill for creating extensions for Shopware Store distribution #1277) or changing which checks run
• project validate