feat(postgres): support CA bundle for SSL verify-ca / verify-full

[kdhillon-stripe]

Summary

• Add stripSslParams helper to remove SSL query params from connection strings before passing to pg, preventing pg's URL parser from overriding the ssl config object.
• Extend sslConfigFromConnectionString with an optional sslCaPem parameter to inject a PEM-encoded CA certificate for verify-ca and verify-full modes.
• Wire ssl_ca_pem config through destination-postgres and state-postgres so users can trust private CAs (e.g. RDS, internal DBs).

Test plan

• Unit tests updated for sslConfigFromConnectionString covering all sslmode values with and without CA
• Unit tests added for stripSslParams
• All assertions verified manually (vitest esbuild binary incompatible with local env; CI will run full suite)
• CI checks pass

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