perf(deps): pick up the cached user-dictionary journal connection

Engine da61ca4 keeps one sqlite connection open for the default journal
instead of opening one and rebuilding the schema per call.
apply_fixed_positions runs on every keystroke, and that open was 90% of the
server-side candidate build under disk load, stalling the task thread long
enough for composition commits to time out and be dropped.

This also advances the engine from the commit develop currently pins to the
merged tip of engine main. Content-wise that is a small step -- 29 files,
mostly additive: fuzzy pinyin options, dictionary state, and their tests.

product-lock.json follows the submodule, so the artifact manifest records the
engine the build actually used and the release gate still sees a merged
engine commit.

product-lock.json

@@ -3,7 +3,7 @@
   "repositories": {
     "engine": {
       "repository": "metasequoiaime/MSIME-Engine",
-      "commit": "111de926d95f11a7c632f857e2967c09d6166ae8"
+      "commit": "da61ca472eda23445ae0ecd2e4d43868063cb36a"
     }
   },
   "dictionary": {