Handles Redis generic key commands: TYPE, UNLINK, RENAME, RENAMENX, COPY, RANDOMKEY, SCAN, EXPIRETIME, PEXPIRETIME, OBJECT, WAIT.

These commands operate on keys regardless of value type. 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

• TYPE key -- returns the type of key ("string" for existing, "none" for missing)
• UNLINK key [key ...] -- async DEL; returns count of deleted keys
• RENAME key newkey -- rename key, error if source missing
• RENAMENX key newkey -- rename only if newkey doesn't exist (1 = renamed, 0 = not)
• COPY source destination [REPLACE] -- copy value+TTL (1 = success, 0 = failure)
• RANDOMKEY -- return a random key, or nil if DB is empty
• SCAN cursor [MATCH pattern] [COUNT count] [TYPE type] -- cursor-based key iteration
• EXPIRETIME key -- absolute Unix timestamp (seconds) when key expires (-1 / -2)
• PEXPIRETIME key -- absolute Unix timestamp (milliseconds) when key expires (-1 / -2)
• OBJECT ENCODING key -- returns actual encoding based on key type
• OBJECT HELP -- returns list of OBJECT subcommands
• OBJECT FREQ key -- returns decayed LFU access frequency counter
• OBJECT IDLETIME key -- returns idle seconds derived from LFU ldt
• OBJECT REFCOUNT key -- always returns 1
• WAIT numreplicas timeout -- returns 0 immediately (no replication)