Handles Redis server commands: PING, ECHO, DBSIZE, KEYS, FLUSHDB, FLUSHALL, INFO, COMMAND, SELECT, LOLWUT, and DEBUG.

Each handler takes the uppercased command name, a list of string arguments, and an injected store map. Returns plain Elixir terms — the connection layer handles RESP encoding.

Supported commands

• PING [message] — returns {:simple, "PONG"} or echoes the message
• ECHO message — returns the message as a bulk string
• DBSIZE — returns the number of keys in the store
• KEYS pattern — returns keys matching a glob pattern (*, ?)
• FLUSHDB [ASYNC|SYNC] — deletes all keys
• FLUSHALL [ASYNC|SYNC] — alias for FLUSHDB (single-db server)
• INFO [section] — returns server information as a bulk string
• COMMAND — returns array of command info tuples
• COMMAND COUNT — returns number of supported commands
• COMMAND DOCS name — returns simplified docs for a command
• COMMAND INFO name [name ...] — returns info for specific commands
• COMMAND LIST — returns all command names
• COMMAND GETKEYS command [args...] — returns which args are keys
• SELECT db — always returns error (not supported)
• LOLWUT [VERSION version] — returns ASCII art with FerricStore branding
• DEBUG SLEEP seconds — sleeps for N seconds (testing only)