ci(lint): build RocksDB 8.9.1 from source

Same fix as build-all.yml: lint.yml's clang-tidy job also installed
librocksdb-dev from Ubuntu 22.04's apt (6.11.4), which CMakeLists.txt
now refuses to configure against. Drop the apt package, add the
shared scripts/ci/build-rocksdb.sh step.

.github/workflows/lint.yml

@@ -56,9 +56,17 @@ jobs:
           sudo apt-get update
           sudo apt-get install -y build-essential cmake ninja-build clang-tidy-15 \
             libboost-all-dev libssl-dev libdb++-dev libleveldb-dev \
-            librocksdb-dev libevent-dev libminiupnpc-dev zlib1g-dev
+            libevent-dev libminiupnpc-dev zlib1g-dev \
+            libsnappy-dev liblz4-dev libzstd-dev
           sudo ln -sf /usr/bin/clang-tidy-15 /usr/local/bin/clang-tidy
 
+      - name: Build RocksDB from source
+        # Ubuntu 22.04's librocksdb-dev is 6.11.4 which CMakeLists.txt now
+        # refuses to configure against (need >= 7.4 for XXH3 per-block
+        # checksum). Build 8.9.1 from source — same version DNS2 ships —
+        # into /usr/local so CMake's find_library picks it up first.
+        run: sudo bash scripts/ci/build-rocksdb.sh
+
       - name: Configure (export compile_commands.json)
         run: |
           cmake -B build -G Ninja \