feat(P.3.6): selection demo — 6 stones + click/box-select wiring

- camera dep 0.2.0 → 0.3.0 (screen_to_world consumer)
- selection dep 0.1.0 added
- 6 stones registered as selectables
- selection.update + render_highlights + render_drag_box wired
- input: lmb + mod_add (shift) + mod_toggle (ctrl)

manifest.module

@@ -7,7 +7,8 @@
     "deps": [
         {"id":"lib-core.maps","version":"0.1.1"},
         {"id":"lib-core.render","version":"0.1.0"},
-        {"id":"lib-core.camera","version":"0.2.0"},
+        {"id":"lib-core.camera","version":"0.3.0"},
+        {"id":"lib-core.selection","version":"0.1.0"},
         {"id":"lib-core.input","version":"0.3.0"},
         {"id":"lib-core.player_control","version":"0.1.0"},
         {"id":"lib-core.interaction","version":"0.1.0"}