fix(theme): drift-guard test, interactive stylebox states, ThemeKeys font consts, richer showcase (whole-branch review)

- build_game_theme.gd: extract build_theme() as a static func returning the
  fully-built Theme; _init() is now a thin save+quit wrapper. Enables a test
  to build a fresh Theme in memory without running the SceneTree main loop.
- test_theme_resource.gd: add test_committed_tres_matches_builder() — builds
  a fresh Theme via the preloaded builder and compares bg_color against the
  committed game_theme.tres for PrimaryCTA/normal, ParchmentCard/panel, and
  DarkPanel/panel. Catches "palette/builder changed, .tres not regenerated."
- build_game_theme.gd: give Tab, TabActive, and Chip explicit hover/pressed/
  focus styleboxes (focus is StyleBoxEmpty to suppress the default ring) so
  they no longer fall back to Godot's default gray button on interaction.
  Add a disabled stylebox + font_disabled_color to PrimaryCTA for the
  unaffordable-CTA state the 2a shell will need.
- theme_keys.gd: add HEADING/ACCENT/MONO font-role consts (kept out of ALL,
  which is stylebox-variation-only); build_game_theme.gd and
  theme_showcase.gd now reference them instead of raw StringName literals.
- theme_showcase.gd: add an italic DM-voice RichTextLabel (EB Garamond
  italic face, spec §6) and two semantic-coloured chips (BLOOD for
  aggressive actions, GOLD for pay/faith) alongside the existing neutral
  chip, demonstrating the script-applied colouring from spec §5.3.
- dark_bay.gdshader: comment noting the stripe uses FRAGCOORD (screen-space)
  while the vignette uses UV (node-local) — intended for full-bleed use.
- surfaces/*.gd: ## comments documenting the accepted deviation from spec
  §5.4 (uniforms set at runtime from Palette rather than baked into the
  .tscn) — no behavior change.
- Regenerated game_theme.tres via build_game_theme.gd.

Full suite: 125/125 (was 124, +1 drift-guard test).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GFDm1ku9WDUacK2S78m2be

client/scripts/theme/theme_showcase.gd

@@ -5,6 +5,7 @@ extends Control
 const Palette = preload("res://scripts/theme/palette.gd")
 const ThemeKeys = preload("res://scripts/theme/theme_keys.gd")
 const GAME_THEME := "res://assets/theme/game_theme.tres"
+const SERIF_ITALIC := "res://assets/theme/fonts/EBGaramond-Italic-VariableFont_wght.ttf"
 
 
 func _ready() -> void:
@@ -22,6 +23,7 @@ func _ready() -> void:
 	col.add_child(_swatches())
 	col.add_child(_variations())
 	col.add_child(_fonts())
+	col.add_child(_prose())
 	col.add_child(_rarity())
 	col.add_child(_bars())
 	col.add_child(_surfaces())
@@ -30,7 +32,7 @@ func _ready() -> void:
 func _heading(text: String) -> Label:
 	var l := Label.new()
 	l.text = text
-	l.theme_type_variation = &"Heading"
+	l.theme_type_variation = ThemeKeys.HEADING
 	return l
 
 
@@ -52,7 +54,7 @@ func _swatches() -> Control:
 		col.add_child(r)
 		var caption := Label.new()
 		caption.text = entry[0]
-		caption.theme_type_variation = &"Mono"
+		caption.theme_type_variation = ThemeKeys.MONO
 		col.add_child(caption)
 		grid.add_child(col)
 	return grid
@@ -64,8 +66,12 @@ func _variations() -> Control:
 	var cta := Button.new(); cta.text = "ENTER THE WORLD"; cta.theme_type_variation = ThemeKeys.PRIMARY_CTA
 	var tab := Button.new(); tab.text = "INACTIVE"; tab.theme_type_variation = ThemeKeys.TAB
 	var tab_a := Button.new(); tab_a.text = "ACTIVE"; tab_a.theme_type_variation = ThemeKeys.TAB_ACTIVE
-	var chip := Button.new(); chip.text = "INTIMIDATE · STR"; chip.theme_type_variation = ThemeKeys.CHIP
-	for b in [cta, tab, tab_a, chip]:
+	# Neutral chip (grey) plus the semantic colours a script applies per-use
+	# (spec §5.3): red for aggressive/combat actions, gold for pay/faith.
+	var chip := Button.new(); chip.text = "STEALTH · DEX"; chip.theme_type_variation = ThemeKeys.CHIP
+	var chip_red := _semantic_chip("INTIMIDATE · STR", Palette.BLOOD)
+	var chip_gold := _semantic_chip("PAY ◈40", Palette.GOLD)
+	for b in [cta, tab, tab_a, chip, chip_red, chip_gold]:
 		row.add_child(b)
 	var card := PanelContainer.new(); card.theme_type_variation = ThemeKeys.PARCHMENT_CARD
 	card.custom_minimum_size = Vector2(160, 80)
@@ -94,6 +100,40 @@ func _variations() -> Control:
 	return row
 
 
+func _semantic_chip(text: String, color: Color) -> Button:
+	# Chip base is neutral (ThemeKeys.CHIP); the semantic colour (§5.3) is set
+	# by the consuming script, here via font-colour + border overrides.
+	var chip := Button.new()
+	chip.text = text
+	chip.theme_type_variation = ThemeKeys.CHIP
+	chip.add_theme_color_override("font_color", color)
+	var tinted := StyleBoxFlat.new()
+	tinted.bg_color = Color(color, 0.15)
+	tinted.border_color = color
+	tinted.set_border_width_all(1)
+	tinted.set_corner_radius_all(3)
+	tinted.content_margin_left = 12
+	tinted.content_margin_right = 12
+	tinted.content_margin_top = 6
+	tinted.content_margin_bottom = 6
+	chip.add_theme_stylebox_override("normal", tinted)
+	return chip
+
+
+func _prose() -> Control:
+	# Narrative italic (spec §6) — the bundled EB Garamond italic face, shown
+	# nowhere else on this screen. RichTextLabel is required for bbcode italics;
+	# a plain Label cannot render [i].
+	var rtl := RichTextLabel.new()
+	rtl.bbcode_enabled = true
+	rtl.fit_content = true
+	rtl.custom_minimum_size = Vector2(900, 0)
+	rtl.add_theme_font_override("normal_font", load(GAME_THEME).default_font)
+	rtl.add_theme_font_override("italics_font", load(SERIF_ITALIC))
+	rtl.text = "[i]The chamber is cold. Something waits in the dark.[/i]"
+	return rtl
+
+
 func _fonts() -> Control:
 	# All three bundled font families, at their real Theme sizes, plus the
 	# default serif body face (not otherwise shown elsewhere on this screen).
@@ -106,12 +146,12 @@ func _fonts() -> Control:
 
 	var accent := Label.new()
 	accent.text = "Vexcca of the Ashmarch"
-	accent.theme_type_variation = &"Accent"
+	accent.theme_type_variation = ThemeKeys.ACCENT
 	col.add_child(accent)
 
 	var mono := Label.new()
 	mono.text = "STR 14 · INITIATIVE +2 · AC 16"
-	mono.theme_type_variation = &"Mono"
+	mono.theme_type_variation = ThemeKeys.MONO
 	col.add_child(mono)
 
 	return col