feat(puppet): v0.3.0 — idle-return locomotion + version bump

- apply_locomotion idle-return: after (now - last_move_time) >
  idle_return_delay, the most-displaced planted leg steps back to its
  current hip position (over idle_step_duration). Group-stagger via
  bumping last_move_time forward by idle_return_stagger.
- M.move_to tracks p.last_move_time when position actually changes.
- README v0.3.0 changelog entry.

init.lua

@@ -438,6 +438,7 @@ function M.move_to(handle, x, y)
         p.facing = math.atan(dy, dx)
         p.last_move_x = x
         p.last_move_y = y
+        p.last_move_time = engine.time.now()
     end
     p.x = x
     p.y = y
@@ -731,6 +732,41 @@ local function apply_locomotion(p, dt)
 
         ::continue::
     end
+
+    if (now - p.last_move_time) > loco.idle_return_delay then
+        local any_stepping = false
+        for i, _ in ipairs(loco.legs) do
+            if p.foot_state[i].state ~= "planted" then any_stepping = true; break end
+        end
+        if not any_stepping then
+            local best_i, best_dist = nil, 0
+            for i, leg_def in ipairs(loco.legs) do
+                local fs = p.foot_state[i]
+                if fs.state == "planted" then
+                    local hip_wx = p.bone_state[leg_def.leg].world.x
+                    local hip_wy = p.bone_state[leg_def.leg].world.y
+                    local d = math.sqrt((hip_wx - fs.anchor_x)^2 + (hip_wy - fs.anchor_y)^2)
+                    if d > best_dist then
+                        best_dist = d
+                        best_i = i
+                    end
+                end
+            end
+            if best_i and best_dist > 1 then
+                local fs = p.foot_state[best_i]
+                local hip_wx = p.bone_state[loco.legs[best_i].leg].world.x
+                local hip_wy = p.bone_state[loco.legs[best_i].leg].world.y
+                fs.state = "stepping"
+                fs.step_from_x = fs.cur_x
+                fs.step_from_y = fs.cur_y
+                fs.step_to_x = hip_wx
+                fs.step_to_y = hip_wy
+                fs.step_timer = 0
+                fs.step_total = loco.idle_step_duration
+                p.last_move_time = now - loco.idle_return_delay + loco.idle_return_stagger
+            end
+        end
+    end
 end
 
 -- ====================================================================