[kclaka]

RESP replies were encoded into empty fixed-size buffers, causing clients to wait indefinitely. Use the growing encoder and cover fragmented commands, pipelined replies, and protocol errors at the transport boundary.

Redis keys now use a binary-safe namespace that cannot overwrite HTTP cache entries. Validate arity, argument types, EX/PX values, unsupported options, and value sizes before mutation. SET without expiration persists until eviction/deletion; TTL returns -1 for persistent keys and -2 for absent keys. Return explicit errors for unsupported EXPIRE, bound incomplete frames to 8 MiB, and cancel client handlers on shutdown. RESP reads no longer update the comparison cache.

Validation: 58 Rust tests (including the prerequisite), including six command/transport regressions; cargo fmt; strict Clippy across all targets. Real TCP smoke checks covered SET/GET/TTL, binary key isolation, malformed SET preservation, and attempted HTTP-key poisoning.

This PR is stacked on #14 because the current CI Rust compiler rejects the original load-generator division code. Merge #14 first; the diff here contains only this improvement family.

Replaces #9 after removing the codex/ branch prefix. Commit contents are preserved; the original PR retains prior discussion and review history.