* Rename WakuMode to LogosDeliveryMode, add Fleet mode
* KernelConf (which starts only kernel) is now a distinct WakuNodeConf (starts messaging, for tests)
* Add LogosDelivery.new(kernelConf) (kernel-only)
* Add LogosDelivery.new(kernelConf, messagingOverrides, channelsOverrides) (full stack)
* LogosDeliveryConf.messagingOverrides/channelsOverrides are Option and mount each layer if present
* Add kernel-only LogosDeliveryConf.init(kernelConf)
* Parse {"mode": "fleet", "kernelConf": {...}} in parseLogosDeliveryConf
* Generalize parseOverrides to parse over caller-supplied defaults
* Add requireMessaging/requireChannels FFI guards and apply them
* Make start/stop skip layers that were not mounted (no config)
* Rename toKernelConf to toWakuNodeConf
* Add tests to test_conf.nim
* Misc additions/refactors
* remove --mode from the CLI
* move WakuMode to the messaging layer
* expose store backend (db url, max connections) and a remote store node on the messaging surface
* wakunode2 with no flags now runs as a full service node (store still opt-in)
* add rateLimitMessagesPerEpoch
* channel rate-limiting auto-enables if epochPeriodSec or messagesPerEpoch is set
* fix JSON conf parser to be generic (works over all config types)
* messaging config = mode + preset + messagingOverrides + channelsOverrides
* add full messaging plus selective kernel config options to MessagingClientConf
* mode (Core/Edge) expands to kernel protocol flags in the messaging layer
* create_node parses the messaging config, drops the flat WakuNodeConf JSON entrypoint
* wire channelsOverrides (segmentation/SDS/rate-limit) into channel creation
* fix liblogosdelivery.h comments and README for the new config shape
* messaging conf tests: switch names, reject-unknown, set-twice, field->kernel
* add kernel log-level, log-format, nodekey to the messaging surface
* Port 0 (ephemeral) default for messaging entry points
* KernelConf alias for WakuNodeConf
* rewrite the FFI examples to the new config shape
* C/C++ examples use preset status.prod
* drop operator-only confs from the examples
* remove duplicate tests & misc test fixes
* Delete p2pReliability from Kernel (Waku) resolver and config (keep preset definition)
* Delete NodeConfig API (deprecation completed by p2pReliability removal from kernel)
* Rename test_messaging_conf.nim to test_conf.nim (tests Logos Delivery config in general)
* Rename messaging_conf_json.nim to logos_delivery_conf_json.nim
* Add logos_delivery_conf.nim (defines LogosDeliveryConf aggregate)
* misc docs/comments cleanups
