[datlechin]

Summary

• PostgreSQL gets Connect Using > Socket. The field takes the socket folder or the .s.PGSQL.<port> file and suggests /tmp and /var/run/postgresql. Port stays visible since it names the socket file. A file path is saved as its folder plus the port from its name.
• The suggestion field is a shared SuggestionComboBox; AWSProfileField now uses it too.
• With Socket selected, the Network tab offers only Direct and hides SSL. The connection signs in with SSL off: libpq never uses TLS on a socket.
• The plugin passes the folder to libpq as host with hostaddr='', so an inherited PGHOSTADDR cannot switch it to TCP. A relative path, a comma, a hidden character or a socket file path over 103 bytes fails before libpq dials (PostgreSQLLocalSocket).
• postgresql:// URLs read host= and port= from the query and a percent-encoded host (%2Ftmp), as libpq does. An empty query port means 5432; an invalid one refuses the URL. Copy Connection String writes postgresql://user@localhost[:port]/db?host=/dir.
• ~/.pgpass matching follows libpq: /tmp as localhost, any other folder by its path, with the socket's port.
• A blank username in ~/.pgpass lookup now means the macOS login name, as in libpq. It used to match literally.
• The form's ~/.pgpass status line updates again; refactor refactor(connection-form): native HIG rebuild + categorized chooser sheet #995 had removed its trigger.
• Backup and Restore pass the folder and port to pg_dump and pg_restore with -h and -p.
• Share links carry the port. Trust, URL matching, the connection list subtitle and the external-link alert name the socket file, so two servers in one folder stay distinct.
• iOS refuses a synced PostgreSQL socket connection, as it does a MySQL one.
• Updated on purpose: tests that used PostgreSQL as the engine without a socket now use Redshift: NetworkPaneLocalSocketTests, SocketPathPlaceholderTests, DatabaseConnectionLocalSocketTests, ConnectionImportLinkSocketTests, ConnectionURLFormatterTests, ConnectionURLParserSocketTests, and iOS ConnectionDetailFormatterTests.

Not in this PR

• A TCP PostgreSQL connection still follows an inherited PGHOSTADDR. Only a socket host pins hostaddr.
• postgresql:///db with no host still asks for a host. libpq would use /tmp; left so a templating mistake is not read as a socket.
• The socket field key is still named on MySQLLocalSocket.fieldKey. Renaming it touches about 35 files across both apps.
• iOS shows a synced PostgreSQL socket as its folder, not the socket file with its port.
• The Linux app was not checked for a PostgreSQL socket mode.

Test plan

• New suites: PostgreSQLLocalSocketTests, ConnectionURLPostgreSQLSocketTests, DatabaseConnectionPostgreSQLSocketTests, NetworkPanePostgreSQLSocketTests, plus NativeDumpRegistryTests and iOS IOSDriverFactoryRefusalTests cases.
• apple/scripts/probes/check-postgresql-local-socket.sh against PostgreSQL 17.11 listening only on its socket with peer auth confirms the libpq behavior the code relies on.
• Real build: the form set to Socket with an empty username returns Connected from Test Connection.
• macOS 682 + 225 cases, iOS 34 cases, lint and localization checks passed locally.

Fixes #3619