Port timing/parity fixes, seamless battle transitions, faithful-res lock, and zoom-aware UI anchoring

Ports from a downstream fork, hand-surgered hunk-by-hunk to exclude the
fork's randomizer/pokescript work and to skip a FixedStep jitter-tolerance
attempt that never fixed the stutter it targeted.

- src/core/Timing.lua: hardware-accurate frame-delay catalog ported from
  pret/pokered, feeding BattleState:waitNext, EffectRegistry's miss/crit
  beats, TextBox/ChoiceBox scroll and prompt holds, and the battle
  silhouette slide/shake/blink/faint timings.
- Seamless battle transitions: Renderer:drawBattleWipe replaces the old
  160x144-only cascade with one wipe drawn over the whole surface at any
  zoom or window size; BattleTransition's per-style frame lengths are
  corrected against pokered-c's derivation; Transition.battleReturn adds
  the post-battle GBFadeInFromWhite the port never had.
- BATTLE SIZE / BATTLE BG options (BattleState:wantsFillScale/bgMode,
  Game.fillScaleInStack/worldBgBattleDim): battle surface can fill the
  window instead of the fixed integer letterbox, and the area around it
  can show white/black/the dimmed overworld instead of only white.
- src/core/FaithfulRes.lua: locks the window to an exact 160x144 multiple.
- Zoom-aware UI anchoring: Renderer:uiScale steps the UI down with survey
  zoom (gated to worldActive so the title/intro never shrink);
  Renderer:setUIAnchor lets TextBox, ChoiceBox, and an opted-in Menu
  (the START menu) pin themselves to a screen edge instead of the
  zoomed-out letterbox.

src/ui/Menu.lua

@@ -50,6 +50,9 @@ function Menu.new(game, items, opts)
   -- only menus whose real mask includes PAD_START -- the start menu
   -- (engine/menus/draw_start_menu.asm) -- opt in here.
   self.startCloses = opts.startCloses or false
+  -- screen-edge anchor for this menu (see Menu:draw); nil keeps it in the
+  -- classic centred letterbox
+  self.anchor = opts.anchor
   self.onCancel = opts.onCancel
   -- BIT_NO_MENU_BUTTON_SOUND (wMiscFlags): the PC session runs its
   -- menus silent (home/window.asm HandleMenuInput_)
@@ -104,6 +107,14 @@ function Menu:update(dt)
 end
 
 function Menu:draw()
+  -- opts.anchor opts a menu out of the centred letterbox and onto a screen
+  -- edge (the START menu asks for "topright").  Only menus that ask for it
+  -- move; every other menu is placed exactly as before.
+  local r = self.anchor and self.game and self.game.renderer
+  if r and r.setUIAnchor then
+    r:setUIAnchor(self.tx * 8, self.ty * 8,
+                  self.tw * 8, self.th * 8, self.anchor)
+  end
   Font.drawBox(self.tx, self.ty, self.tw, self.th)
   love.graphics.setColor(0, 0, 0, 1)
   local visible = (self.maxVisible and math.min(self.maxVisible, #self.items))