* fix: skip Docker check in ensure-postgres.sh when remote DATABASE_URL is set
When DATABASE_URL points to a non-localhost host, the script now skips
all Docker operations and only verifies remote DB connectivity via
pg_isready directly.
* fix: honor DATABASE_URL for remote postgres preflight
* fix(make): clarify stop output for remote database
* docs: add local deployment protocol guidance to SELF_HOSTING.md
Clarify that local deployments without TLS should use http:// and ws://
instead of https:// and wss://.
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Co-authored-by: Junlong Liu <junlong.liu@shopee.com>
