refactor: build against the single liblogosdelivery library (#116)

* refactor: build against the single liblogosdelivery library

logos-delivery#4012 unifies the node lifecycle on logosdelivery_* and ships the
full API — Messaging, Reliable Channels, and the low-level Kernel (waku_*) tier
— in one liblogosdelivery library, retiring the separate libwaku. Migrate the
bindings onto it.

- internal/ffi: collapse the two bridges into one internal/ffi/liblogosdelivery
  over the single library. The kernel wrappers keep calling waku_* (kernel
  header), the lifecycle now uses logosdelivery_create_node/start_node/
  stop_node/destroy (waku_new/start/stop/destroy are gone), events use
  logosdelivery_set_event_callback. Include liblogosdelivery_kernel.h (which
  re-exports the stable header) and link -llogosdelivery. Remove
  internal/ffi/libwaku.
- pkg/kernel: repoint at internal/ffi/liblogosdelivery; the Makefile links
  -llogosdelivery.
- CI: build only `make liblogosdelivery`, headers from library/, single
  -llogosdelivery. Pinned to logos-delivery#4012 until it merges (see the
  TODO/LOGOS_DELIVERY_REF in pr.yml).

The high-level MessagingClient (pkg/messaging) lands in a follow-up PR on top.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* fix(kernel): drop removed config keys + add a runnable example

Running against the single liblogosdelivery library surfaced a config drift:
the consolidated WakuNodeConf strictly rejects unknown keys, and
common.WakuConfig still emitted `legacyStore` (removed upstream, and sent
unconditionally) and `host` (renamed to `listenAddress`). That failed node
creation, so every kernel test that starts a node failed. Reconcile the config:

- drop the LegacyStore field (and its two obsolete test references; the
  already-skipped TestCheckLegacyStore keeps compiling);
- map Host to the `listenAddress` JSON key.

Add examples/kernel: a small runnable check that drives the unified lifecycle
(logosdelivery_create_node/start/stop/destroy) and a few kernel ops (version,
listen addresses, is-online, relay subscribe/unsubscribe) over the single
library. `go run ./examples/kernel` prints OK.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* fix(kernel): correct RelayPublish wire format; verify send/receive

RelayPublish marshalled the generated protobuf (content_topic), but the library
requires the WakuMessage wire format (contentTopic) and rejected it with
"Missing required field: contentTopic". Marshal the wire shape explicitly.

Turn examples/kernel into an end-to-end send/receive check: two relay nodes on
cluster 16 / shard 64, connected via the listen multiaddr, one publishes and the
other receives it off MsgChan. Verified against a locally-built liblogosdelivery:
prints "send/receive OK".

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* ci: build against logos-delivery master (unpin #4012)

logos-delivery#4012 merged, so drop the LOGOS_DELIVERY_REF pin and clone the
default branch; the cache key tracks master's HEAD again.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* refactor(ffi): flatten internal/ffi/liblogosdelivery into internal/ffi

With a single library there is no bridge to choose between, so the extra
subpackage adds nothing: move the bridge to internal/ffi (package ffi) and drop
the umbrella doc. pkg/kernel now imports internal/ffi and calls ffi.*.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* test(kernel): add a two-node relay send/receive integration test

TestRelaySendReceive connects two relay nodes, publishes a random payload from
one and requires the other to receive it — end-to-end over the single library.
Compiled by the PR gate; run under `make test` / locally against a built
liblogosdelivery. (Replaces the former examples/kernel, removed alongside the
ffi flatten.)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* refactor(ffi): keep two files in package ffi, one per header

The single library still ships two headers — liblogosdelivery.h (stable
Messaging/lifecycle) and liblogosdelivery_kernel.h (low-level waku_*). Mirror
that with two files in one package instead of one merged ffi.go: keep the
messaging bridge and all the shared plumbing (Handle/RetOK/lifecycle/callbacks/
call) in liblogosdelivery.go, and keep the kernel wrappers in libwaku.go, which
reuses the shared call + logosGoCallback. This is the same two files we had,
moved into package ffi — a much smaller diff than the merge.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* Apply suggestions from code review

Co-authored-by: Ivan FB <128452529+Ivansete-status@users.noreply.github.com>

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Co-authored-by: Ivan FB <128452529+Ivansete-status@users.noreply.github.com>

.github/workflows/pr.yml

@@ -17,12 +17,10 @@ jobs:
       # Clone the logos-delivery checkout OUTSIDE the module tree: a directory
       # named `vendor/` at the module root would put Go into vendor mode.
       LOGOS_DELIVERY_DIR: ${{ github.workspace }}/.logos-delivery
-      # Both kernel (libwaku) and messaging (liblogosdelivery) headers are on
-      # the include path so every package compiles. `-l` is deliberately NOT
-      # set here: each internal/ffi subpackage selects its own library via a
-      # `#cgo LDFLAGS` directive, so no binary links both libs (they export
-      # overlapping symbols until logos-delivery#3851).
-      CGO_CFLAGS: -I${{ github.workspace }}/.logos-delivery/library/ -I${{ github.workspace }}/.logos-delivery/liblogosdelivery/
+      # The single liblogosdelivery library exposes the full API; its headers
+      # live in library/. The bridge self-links -llogosdelivery via a #cgo
+      # directive, so no -l is set here.
+      CGO_CFLAGS: -I${{ github.workspace }}/.logos-delivery/library/
       CGO_LDFLAGS: -L${{ github.workspace }}/.logos-delivery/build/ -Wl,-rpath,${{ github.workspace }}/.logos-delivery/build/
       # Build in module mode; never use a vendor/ dir.
       GOFLAGS: -mod=mod
@@ -39,9 +37,8 @@ jobs:
           go-version: "1.24"
 
       - name: Resolve logos-delivery commit
-        # Cache the built libraries keyed on the exact upstream commit, so the
-        # expensive clone + build is skipped while logos-delivery's HEAD is
-        # unchanged. ls-remote gives us the SHA before we clone.
+        # Cache the built library keyed on the exact upstream commit, so the
+        # expensive clone + build is skipped while master's HEAD is unchanged.
         id: logos-delivery-rev
         run: |
           rev=$(git ls-remote https://github.com/logos-messaging/logos-delivery.git HEAD | cut -f1)
@@ -58,9 +55,9 @@ jobs:
         if: steps.logos-delivery-cache.outputs.cache-hit != 'true'
         run: git clone --depth 1 https://github.com/logos-messaging/logos-delivery.git "$LOGOS_DELIVERY_DIR"
 
-      - name: Build libwaku + liblogosdelivery
+      - name: Build liblogosdelivery
         if: steps.logos-delivery-cache.outputs.cache-hit != 'true'
-        run: make -C "$LOGOS_DELIVERY_DIR" libwaku liblogosdelivery -j
+        run: make -C "$LOGOS_DELIVERY_DIR" liblogosdelivery -j
 
       - name: go build
         run: go build ./...
@@ -88,9 +85,9 @@ jobs:
 
       - name: go test messaging (run)
         # Fast, network-free unit tests for the Messaging API + its ffi bridge.
-        run: go test ./pkg/messaging/... ./internal/ffi/liblogosdelivery/...
+        run: go test ./pkg/messaging/... ./internal/ffi/...
 
       - name: go test kernel (compile)
         # The kernel suite is heavy integration (runs nightly in CI.yml), so
         # only compile its test binaries here.
-        run: go test -run '^$' ./pkg/kernel/... ./internal/ffi/libwaku/...
+        run: go test -run '^$' ./pkg/kernel/...