Bugfixes, add INFO command, graceful shutdown. elimitate dead code

- Remove unsed handleClientKill, handleClientKill
- Fix misleading error message on rate limit
- Eliminated unused channel-to-pattern index that was causing unnecessary work
- Fixed O(n²) duplicate check in PublishToPattern
- Limit total pattern subscriptions to 10,000
- Limit channel subscriptions per client to 10,000
- Added INFO command
- Added graceful shutdown timeout
- Validate that log directory is writable during config load
- Make SELECT properly handle whitespace around DB index like Redis
- Return proper error instead of empty array for unsupported commands on sharded pubsub stubs
- More accurate error messages throughout
- Updated README.md

Makefile

@@ -38,7 +38,7 @@ endif
 VERSION_STRING := $(_VERSION)
 
 # Build flags
-LDFLAGS := -s -w -X main.version=$(VERSION_STRING)
+LDFLAGS := -s -w -X main.version=$(VERSION_STRING) -X github.com/eleksir/pekoe/internal/server.Version=$(VERSION_STRING)
 
 .PHONY: all
 all: clean build