format-requirements

[general-kroll-4-life]

Extended query protocol support with error recovery

Summary

• Implement full extended query protocol (Parse, Bind, Describe, Execute, Close, Sync, Flush) with proper wire message parsing and serialization
• Add IExtendedQueryBackend interface with opt-in support via type assertion; DefaultExtendedQueryBackend delegates to simple query path for backwards compat
• Restructure command loop: ReadyForQuery sent once initially, then only after SimpleQuery completion and Sync (per PostgreSQL protocol spec)
• Add error state tracking: after extended query failure, discard messages until Sync, then send ReadyForQuery('E') matching PostgreSQL behavior
• Fix ClientClose ('C') to close prepared statements/portals, not the connection; connection close moved to ClientTerminate ('X') where it belongs
• Add text format bypass in Column.Write: string/[]byte sources write raw bytes directly, preserving exact backend representation (e.g. sqlite "t"/"f" for bools)
• Thread resultFormats from Bind through to RowDescription and data encoding, supporting per-column text/binary format selection per protocol spec
• Per-connection PreparedStatement and Portal caches
• Enable previously disabled pgx query test
• Add comprehensive test coverage: extended query happy path, error recovery (Parse/Bind/Describe/Execute errors), statement/portal lifecycle, multiple Sync recovery, simple query after extended query error, text bypass preservation, resolveResultFormat protocol rules, sqlbackend unit tests
• Soft linting.
• Better doco.