perf(sync): the fork's signed commit with fast merges, and #150 fixed

The offline sync package's shared part now comes from the fork's branch
halkyon/fast-merges (f062725, signed), adding two changes to the pin: a
merge only inserting new rows proven unable to change the projection
skips its passes (a rating another device made, received in a library of
8,000 cards: 9.5 s, now about 60 ms), and projections are rebuilt once
after the synced tables changed rather than on every session and merge
(upstream #150). AGENTS.md's note on #150 stays until a deploy runs it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

pubspec.lock

@@ -1578,8 +1578,8 @@ packages:
     dependency: "direct overridden"
     description:
       path: "packages/serverpod_offline_sync"
-      ref: b5450353b98240a1bd6f4471815a8be94c91ce5b
-      resolved-ref: b5450353b98240a1bd6f4471815a8be94c91ce5b
+      ref: f062725a16fffa1be8cf9141cdbfefae209598ea
+      resolved-ref: f062725a16fffa1be8cf9141cdbfefae209598ea
       url: "https://code.halkyon.app/project-halkyon/serverpod-offline-sync.git"
     source: git
     version: "0.0.10"