feat(map-editor): cell-tile as third state.mode + Tools menu entry

state.set_mode now accepts "cell-tile"; toggle_mode is renamed
cycle_mode (with a backwards-compat alias) and now advances
auto-tile -> cell-tile -> direct -> auto-tile. Tools > Mode
submenu gains a third entry between Auto-Tile and Direct.
Self-test gains t8 (set/get round-trip) and t12 (cycle order).
Startup banner updated to "Tab=cycle mode". Manifest dep pin
bumped to lib-core.maps 0.5.7 to match installed version.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

init.lua

@@ -133,13 +133,23 @@ local state = (function()
     function M.is_picker_open()        return state.picker_open end
 
     -- 0.2.0a: binary mode switch (Auto-Tile vs Direct).
+    -- CT6: extended to three-way cycle (auto-tile / cell-tile / direct).
     function M.get_mode()              return state.mode end
     function M.set_mode(m)
-        if m == "auto-tile" or m == "direct" then state.mode = m end
+        if m == "auto-tile" or m == "cell-tile" or m == "direct" then state.mode = m end
     end
-    function M.toggle_mode()
+    function M.cycle_mode()
-        state.mode = (state.mode == "auto-tile") and "direct" or "auto-tile"
+        if state.mode == "auto-tile" then
+            state.mode = "cell-tile"
+        elseif state.mode == "cell-tile" then
+            state.mode = "direct"
+        else
+            state.mode = "auto-tile"
         end
+    end
+    -- Backwards-compat alias (still called by the input binding and the
+    -- toolbar mode toggle in older code paths; both now cycle 3 modes).
+    M.toggle_mode = M.cycle_mode
 
     function M.is_modal_open(id)
         if id == nil then return state.modal_open ~= nil end
@@ -548,6 +558,9 @@ local ui = (function()
             { type = "toggle", label = "Auto-Tile",
               is_on = function() return mode_is("auto-tile") end,
               fire  = function() actions.set_mode("auto-tile") end },
+            { type = "toggle", label = "Cell-Tile",
+              is_on = function() return mode_is("cell-tile") end,
+              fire  = function() actions.set_mode("cell-tile") end },
             { type = "toggle", label = "Direct", hotkey = "Tab",
               is_on = function() return mode_is("direct") end,
               fire  = function() actions.set_mode("direct") end },
@@ -1464,7 +1477,7 @@ input.bind("reset_transform",   { "0" })     -- 0.2.0c
 input.bind("toggle_debug_overlay", { "d" })  -- 0.2.0c.3
 input.bind("toggle_world_overlay", { "g" })  -- 0.2.0c.4
 
-engine.print("map-editor v0.3.0: ready. Tab=mode, I=help, G=grid, D=debug, S=save, E=erase, R=rotate, H=flip, 0=reset, ESC=quit / close")
+engine.print("map-editor v0.3.0: ready. Tab=cycle mode, I=help, G=grid, D=debug, S=save, E=erase, R=rotate, H=flip, 0=reset, ESC=quit / close")
 
 -- =====================================================================
 -- 0.3.0: self-tests (Spec §7.1). Run once on the first CI frame.
@@ -1541,6 +1554,20 @@ local function self_test()
     engine.test.equals(state.is_layer_visible(lname), not vis_before,
         "t7: layer visibility flipped via state.toggle_layer_visible")
     state.toggle_layer_visible(lname)
+
+    -- t8: state.set_mode accepts "cell-tile"
+    state.set_mode("cell-tile")
+    engine.test.equals(state.get_mode(), "cell-tile",
+        "t8: set_mode('cell-tile') sets mode")
+
+    -- t12: cycle_mode cycles auto -> cell -> direct -> auto
+    state.set_mode("auto-tile")
+    state.cycle_mode()
+    engine.test.equals(state.get_mode(), "cell-tile", "t12: cycle auto -> cell")
+    state.cycle_mode()
+    engine.test.equals(state.get_mode(), "direct", "t12: cycle cell -> direct")
+    state.cycle_mode()
+    engine.test.equals(state.get_mode(), "auto-tile", "t12: cycle direct -> auto")
 end
 
 -- =====================================================================

manifest.module

@@ -9,7 +9,7 @@
         "blob_rect_stone": "lib-asset.prototype-blob-geom"
     },
     "deps": [
-        {"id":"lib-core.maps","version":"0.5.6"},
+        {"id":"lib-core.maps","version":"0.5.7"},
         {"id":"lib-core.render","version":"0.1.0"},
         {"id":"lib-core.camera","version":"0.3.0"},
         {"id":"lib-core.input","version":"0.4.0"},