Fix lobby/HUD UI pinned at (0,0); shrink player hitbox below visual size

The lobby connect menu and three pieces of the HUD (hit-flash overlay, boss
bar centering, death-message centering, hint label) were all silently broken
by the same Godot gotcha: set_anchors_preset(preset) with the default
keep_offsets=false does NOT zero the offsets to the preset's margins -- it
recomputes them to preserve the control's *current* rect, which for a
freshly constructed Control is (0,0). Anchors end up correct; the actual
rect stays pinned to the top-left corner regardless. Fixed by switching to
set_anchors_and_offsets_preset() everywhere a Control is built in code, and
by using offset_left/offset_top (anchor-relative) instead of .position
(absolute) for the HUD hint label. Documented as gotcha #5 in CLAUDE.md.

Also split PLAYER_RADIUS into two constants: PLAYER_RADIUS (6.0, the
authoritative hitbox used by SimWorld) and PLAYER_VISUAL_RADIUS (13.0,
view-only, used by world_view.gd). The client renders every ship a little
late relative to the server -- interpolation delay, reconciliation
smoothing -- so a hitbox that matched the sprite would let bullets connect
against a ship the player watched dodge clear of them. A smaller hitbox
means the occasional bullet visibly clips the sprite without a hit, which
reads as more forgiving of latency than the reverse.

Verified headlessly: a throwaway scene instantiating MainMenu/HUD under a
real 1280x720 viewport, asserting the panel is centered and _canvas.size /
hint position resolve correctly, before and after each fix. check.sh,
test.sh (78/78) and smoke.sh all pass.

CLAUDE.md

@@ -87,7 +87,16 @@ ticks in milliseconds with no SceneTree.
 4. **Input events default to `device = 16`, which matches nothing.** Bindings
    must use `device = -1`. `tools/setup_input_map.gd` generates the input map
    correctly; edit that file, not the `[input]` block in `project.godot`.
-5. **`ProjectSettings.save()` drops settings equal to the engine default** and
+5. **`set_anchors_preset(preset)` does not zero the offsets.** `keep_offsets`
+   defaults to `false`, which despite the name means "recompute offsets to keep
+   the control's *current* rect on screen" — for a freshly created Control that
+   rect is `(0,0)`-sized, so it comes out pinned to the top-left corner
+   regardless of the anchors. Use `set_anchors_and_offsets_preset()` for any
+   Control built in code. Separately: `.position` assigns an *absolute*
+   coordinate even on an anchored control; `offset_left`/`offset_top` are the
+   anchor-relative ones. This combination silently broke the main menu and
+   three pieces of the HUD.
+6. **`ProjectSettings.save()` drops settings equal to the engine default** and
    strips comments. Anything load-bearing (the 60 Hz tick) is asserted in code
    in `src/main.gd` instead of trusted to `project.godot`.
 

src/core/sim_config.gd

@@ -19,7 +19,16 @@ const BULLET_CULL_MARGIN := 64.0
 
 # --- Player -----------------------------------------------------------------
 const PLAYER_SPEED := 240.0
-const PLAYER_RADIUS := 9.0
+## Authoritative hitbox. Smaller than PLAYER_VISUAL_RADIUS on purpose: a client
+## renders its own and everyone else's ship a little late (interpolation delay,
+## reconciliation smoothing), so a hitbox that matched the sprite exactly would
+## let bullets connect against a ship the player watched dodge clear of them.
+## Erring small means the occasional bullet visibly clips the ship without a
+## hit -- a client-side illusion, but the one that reads as fair, versus a
+## bullet that visibly missed still registering as a hit.
+const PLAYER_RADIUS := 6.0
+## Render-only. Used by src/view/, never by anything under src/sim/.
+const PLAYER_VISUAL_RADIUS := 13.0
 const PLAYER_MAX_HP := 100
 const PLAYER_FIRE_COOLDOWN := 7          # ticks
 const PLAYER_BULLET_SPEED := 620.0

src/ui/hud.gd

@@ -16,15 +16,27 @@ var client: ClientRuntime = null
 func _ready() -> void:
 	layer = 10
 	_canvas = Control.new()
-	_canvas.set_anchors_preset(Control.PRESET_FULL_RECT)
+	# set_anchors_preset() alone leaves the offsets at whatever preserves the
+	# control's rect at the moment of the call -- (0,0)-sized for a brand new
+	# node, regardless of the anchors -- so _canvas.size silently stayed
+	# (0, 0) forever. That took the hit-flash overlay, the boss bar centering
+	# and the death-message centering down with it, since all three read
+	# _canvas.size. set_anchors_and_offsets_preset() sets both correctly.
+	_canvas.set_anchors_and_offsets_preset(Control.PRESET_FULL_RECT)
 	_canvas.mouse_filter = Control.MOUSE_FILTER_IGNORE
 	_canvas.draw.connect(_draw_hud)
 	add_child(_canvas)
 
 	_status = _make_label(Vector2(MARGIN, MARGIN))
 	_hint = _make_label(Vector2(MARGIN, 0.0))
-	_hint.set_anchors_preset(Control.PRESET_BOTTOM_LEFT)
-	_hint.position = Vector2(MARGIN, -56.0)
+	_hint.set_anchors_and_offsets_preset(Control.PRESET_BOTTOM_LEFT)
+	# `.position` assigns an ABSOLUTE coordinate regardless of anchors (that's
+	# what stranded this label off-screen despite the anchor being correct).
+	# offset_left/offset_top are the anchor-relative ones -- negative offset_top
+	# here means "56px above the bottom anchor", which is what "-56" was meant
+	# to say in the first place.
+	_hint.offset_left = MARGIN
+	_hint.offset_top = -56.0
 
 
 func _make_label(pos: Vector2) -> Label:

src/ui/main_menu.gd

@@ -12,13 +12,27 @@ var _status: Label
 
 
 func _ready() -> void:
-	set_anchors_preset(Control.PRESET_FULL_RECT)
+	# set_anchors_preset(preset, keep_offsets=false) does NOT zero the offsets
+	# to the preset's canonical margins -- despite the parameter name, false
+	# means "recompute offsets to keep the control's CURRENT rect visually
+	# unchanged". For a freshly constructed Control that rect is (0,0)-sized
+	# at the origin, so the offsets come out as whatever preserves exactly
+	# that: a zero rect pinned to (0,0), regardless of the anchors. This is
+	# what actually caused the "menu stuck in the top-left corner" bug --
+	# set_anchors_and_offsets_preset() sets both halves correctly in one call.
+	set_anchors_and_offsets_preset(Control.PRESET_FULL_RECT)
+
+	# A CenterContainer recomputes its child's centered position itself, every
+	# time the child's minimum size or the window size changes -- no manual
+	# offset math to get wrong.
+	var center := CenterContainer.new()
+	center.set_anchors_and_offsets_preset(Control.PRESET_FULL_RECT)
+	add_child(center)
+
 	var panel := VBoxContainer.new()
-	panel.set_anchors_preset(Control.PRESET_CENTER)
 	panel.custom_minimum_size = Vector2(360.0, 0.0)
 	panel.add_theme_constant_override("separation", 8)
-	panel.position = Vector2(-180.0, -160.0)
-	add_child(panel)
+	center.add_child(panel)
 
 	var title := Label.new()
 	title.text = "TRANSCIENCE"

src/view/world_view.gd

@@ -103,8 +103,13 @@ func _draw_local_player() -> void:
 		_draw_escape_ring(client.predicted_pos, client.my_escape, COL_LOCAL)
 
 
+## Drawn at PLAYER_VISUAL_RADIUS, larger than the PLAYER_RADIUS hitbox actually
+## used for hits -- see the comment on those constants in sim_config.gd. The
+## mismatch is deliberate, not a placeholder: a bullet can visibly clip the
+## sprite without registering a hit, which reads as more forgiving of latency
+## than the reverse.
 func _draw_ship(pos: Vector2, aim: float, col: Color, alive: bool) -> void:
-	var r := SimConfig.PLAYER_RADIUS
+	var r := SimConfig.PLAYER_VISUAL_RADIUS
 	draw_circle(pos, r, Color(col, 0.4 if alive else 0.2))
 	draw_arc(pos, r, 0.0, TAU, 20, col, 2.0)
 	if alive:
@@ -115,5 +120,5 @@ func _draw_ship(pos: Vector2, aim: float, col: Color, alive: bool) -> void:
 ## The escape channel is drawn on the player, not just in the HUD, so other
 ## players can see someone is about to leave and react.
 func _draw_escape_ring(pos: Vector2, progress: float, col: Color) -> void:
-	draw_arc(pos, SimConfig.PLAYER_RADIUS + 8.0, -PI * 0.5,
+	draw_arc(pos, SimConfig.PLAYER_VISUAL_RADIUS + 8.0, -PI * 0.5,
 		-PI * 0.5 + TAU * progress, 32, Color(col, 0.9), 3.0)