refactor(selection): remove prev_click_down, use input.was_action_released (P.3.10)

Behavior identical. lib-core.input dep bump 0.3.0 → 0.4.0.
Resolves audit I1 (RTS-Tech-Demo-Audit 2026-05-14).

init.lua

@@ -8,6 +8,9 @@
 -- action-names (mod_add, mod_toggle). AABB-Hit-Test (last-registered-wins).
 -- Render: alpha-tinted draw_rect helpers (kein Outline).
 --
+-- P.3.10 patch (2026-05-15): prev_click_down workaround removed.
+-- Uses lib-core.input v0.4.0 was_action_released. Behaviorally identical.
+--
 -- DEPRECATED-MVPs siehe Spec §7 + inline-comments unten.
 -- =====================================================================
 
@@ -28,7 +31,6 @@ local press_y         = 0
 local cur_x           = 0
 local cur_y           = 0
 local drag_threshold  = 4         -- px
-local prev_click_down = false     -- release-edge detection
 
 -- Bindings.
 local click_action      = nil
@@ -308,15 +310,11 @@ end
 -- Per-Frame
 
 function M.update(dt)
-    -- Release-edge detection must sync EVERY frame (even when disabled or unbound)
-    -- so prev_click_down doesn't drift across enable/disable boundaries.
-    local cur_down = (click_action ~= nil) and input.is_action_down(click_action) or false
-    local released = (prev_click_down and not cur_down)
-    prev_click_down = cur_down
-
     if not enabled_flag then return end
     if click_action == nil then return end
 
+    local released = input.was_action_released(click_action)
+
     local mx, my = engine.input.get_mouse_pos()
 
     if drag_state == "idle" then
@@ -380,8 +378,6 @@ function M.render_highlights()
     end
 end
 
--- DEPRECATED-MVP: was_action_released in lib-core.input (currently tracked internally
---                 via prev_click_down — promote to input-lib when 2nd consumer needs it)
 -- DEPRECATED-MVP: pixel-perfect click hit-test (needs sprite-API + opacity-mask)
 -- DEPRECATED-MVP: register(aabb_fn, z) z-order disambiguator
 -- DEPRECATED-MVP: on_changed(fn) observer-callback (polling-API sufficient for RTS-MVP)