fix(theme-guard): close the drift guard's third miss — the meta-guard's own continue whitelisted the gap

test_committed_tres_matches_builder has now been "fixed" three times (traps.md #12).
v1 hardcoded 3 checks; v2 iterated ThemeKeys.ALL but missed the six font roles; v3
added a meta-guard specifically to catch "the builder styles a thing guarded by
nothing" — but that meta-guard contained `if fresh.get_type_variation_base(variation)
== &"": continue`, which whitelisted exactly the case it was built to catch. The
builder styles RichTextLabel directly (build_game_theme.gd's _rich_text()), with no
set_type_variation, so it reports base "" and was skipped unconditionally — and
RichTextLabel is what renders every line of DM prose the creation screen shows
(_origin_text, _detail_blurb). Nothing compared its fonts, font size, or colour, nor
the theme-level default_font/default_font_size, against the committed .tres.

Adds ThemeKeys.BASE_TYPES for base Control types the builder styles directly, folds
it into the drift guard's coverage, replaces the meta-guard's continue with an
assertion that names the offending type, and adds the missing theme-level default
font/size comparison. Proved with three reverted breaks: a RichTextLabel font-size
edit, a theme-level default_font_size edit, and an unregistered "GhostRole" variation
— all three now go red and name the drifted property.

Also: strengthens test_creation_copy's error-copy sweep to assert a mapped error
actually reaches its authored line rather than silently falling through to the
generic UNSPOKEN fallback (CreationCopy.UNSPOKEN satisfied all four prior checks,
so a renamed validator string could regress silently); and removes two assertions
that were true by construction / already true before their test's action ran.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

client/tests/unit/test_theme_resource.gd

@@ -30,14 +30,19 @@ func test_default_font_is_set():
 
 
 func _guarded_variations() -> Array:
-	# EVERY variation the builder touches — the stylebox variations (ThemeKeys.ALL)
-	# AND the six font roles (ThemeKeys.FONT_ROLES), which ALL deliberately excludes
-	# by its own docstring. Iterating ALL alone left every font, font size and font
-	# colour in the theme unguarded: change Palette.CREAM (TitleLogo's font colour,
-	# and nothing else's), skip the rebuild, and the suite stayed green with a stale
-	# .tres shipped. traps.md #12 — "covers everything" must iterate the full set.
+	# EVERY variation OR BASE TYPE the builder touches — the stylebox variations
+	# (ThemeKeys.ALL), the six font roles (ThemeKeys.FONT_ROLES), AND the base
+	# types the builder styles directly with no variation on top
+	# (ThemeKeys.BASE_TYPES — today just RichTextLabel). ALL and FONT_ROLES
+	# deliberately exclude each other's half by their own docstrings; missing
+	# BASE_TYPES here left RichTextLabel's two fonts, its font size and its
+	# font colour — the ONLY things rendering DM prose on the creation screen —
+	# unguarded against a stale .tres. traps.md #12, the third miss: iterating
+	# ALL alone, then ALL+FONT_ROLES, both still left a gap "covers everything"
+	# did not actually cover.
 	var out: Array = ThemeKeys.ALL.keys()
 	out.append_array(ThemeKeys.FONT_ROLES.keys())
+	out.append_array(ThemeKeys.BASE_TYPES.keys())
 	return out
 
 
@@ -57,7 +62,22 @@ func test_the_drift_guard_covers_every_variation_the_builder_touches():
 		if not touched:
 			continue
 		if fresh.get_type_variation_base(variation) == &"":
-			continue        # a BASE type (the builder styles RichTextLabel directly), not a variation
+			# "" means one of two things, and they must be told apart, not both
+			# waved through: (a) a KNOWN base type the builder styles directly
+			# with no set_type_variation (RichTextLabel today — registered in
+			# ThemeKeys.BASE_TYPES), or (b) a type nobody ever registered at
+			# all — styled with set_stylebox/set_font/set_color but never
+			# given a set_type_variation, which reports the same "" and used
+			# to slip through this `continue` forever. The old guard could not
+			# tell these apart because it treated "" as "definitely (a)" and
+			# skipped it unconditionally — the exact whitelist that let
+			# RichTextLabel through in the first place (traps.md #12, third
+			# miss). Assert (a); anything else IS (b) and must be named.
+			assert_true(variation in ThemeKeys.BASE_TYPES,
+				("the builder styles %s directly (no set_type_variation) and it is not in " +
+				"ThemeKeys.BASE_TYPES — add it there, or if it should be a real variation, " +
+				"give it a set_type_variation(...) base so ALL/FONT_ROLES can guard it") % variation)
+			continue
 		assert_true(variation in guarded,
 			"the builder styles the variation %s but no drift guard walks it — add it to ThemeKeys.ALL or ThemeKeys.FONT_ROLES" % variation)
 
@@ -75,6 +95,18 @@ func test_committed_tres_matches_builder():
 	var fresh: Theme = Builder.build_theme()
 	var committed: Theme = load(THEME_PATH)
 
+	# Theme-LEVEL defaults (build_game_theme.gd:69-70) live on the Theme object
+	# itself, not under any type or variation, so no per-variation loop below
+	# ever reaches them — they need their own comparison or a changed
+	# default_font_size (18 -> anything) ships silently. Font by resource_path,
+	# not the Resource: load() caches, so two references to the same .ttf are
+	# `==` even when the builder swapped fonts, unless the .tres happens to
+	# still point at the same file.
+	assert_eq(committed.default_font.resource_path, fresh.default_font.resource_path,
+		"stale game_theme.tres — theme.default_font drifted from the builder; re-run build_game_theme.gd")
+	assert_eq(committed.default_font_size, fresh.default_font_size,
+		"stale game_theme.tres — theme.default_font_size drifted from the builder; re-run build_game_theme.gd")
+
 	for variation in _guarded_variations():
 		for state in fresh.get_stylebox_list(variation):
 			assert_true(committed.has_stylebox(state, variation),