Include starting_position_index in UnknownUnit view (#4584)

The starting_position_index field was not being included in the
UnitView for hidden/unplaced enemy units, causing GameStateGuesser
to default it to -1. This caused crashes in PlayerSetupCommandFactory
when the AI tried to generate setup commands for attacker units.

starting_position_index is public information (defenders know which
direction attackers will spawn from), so it should always be visible.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude <noreply@anthropic.com>

src/main/cpp/net/eagle0/shardok/library/view_filters/UnitFilter.cpp

@@ -19,7 +19,13 @@ using net::eagle0::shardok::api::UnitView;
 using net::eagle0::shardok::common::CommandType;
 using std::vector;
 
-auto UnknownUnit(UnitId uid, PlayerId pid, BattalionTypeId bt, int size, bool hidden) -> UnitView;
+auto UnknownUnit(
+        UnitId uid,
+        PlayerId pid,
+        BattalionTypeId bt,
+        int size,
+        bool hidden,
+        int8_t startingPositionIndex) -> UnitView;
 
 [[nodiscard]] auto UnitFilteredForPlayer(
         const SettingsGetter &settings,
@@ -36,7 +42,8 @@ auto UnknownUnit(UnitId uid, PlayerId pid, BattalionTypeId bt, int size, bool hi
                 unit->player_id(),
                 unit->battalion().type(),
                 unit->battalion().size(),
-                true);
+                true,
+                unit->starting_position_index());
     }
     if (IsUnplaced(unit->location()) && !visibleToAsker) {
         return UnknownUnit(
@@ -44,7 +51,8 @@ auto UnknownUnit(UnitId uid, PlayerId pid, BattalionTypeId bt, int size, bool hi
                 unit->player_id(),
                 unit->battalion().type(),
                 unit->battalion().size(),
-                false);
+                false,
+                unit->starting_position_index());
     }
 
     UnitView filtered{};
@@ -142,7 +150,8 @@ auto UnknownUnit(
         const PlayerId pid,
         BattalionTypeId bt,
         const int size,
-        const bool hidden) -> UnitView {
+        const bool hidden,
+        const int8_t startingPositionIndex) -> UnitView {
     UnitView uv;
     uv.set_unit_id(uid);
     uv.set_player_id(pid);
@@ -154,6 +163,11 @@ auto UnknownUnit(
     uv.mutable_battalion()->set_size(size);
     uv.set_hidden(hidden);
 
+    // starting_position_index is public info - defenders know attacker spawn directions
+    if (startingPositionIndex != -1) {
+        uv.mutable_starting_position_index()->set_value(startingPositionIndex);
+    }
+
     uv.set_my_knowledge(0);
 
     return uv;