refactor(theme): migrate shared packages to --color-* token naming

Several shared-ui / shared-auth-ui / subscriptions / credits
components used shadcn-style bare CSS variables (--muted, --primary,
--foreground, etc.), but the Mana theme system standardized on
--color-*. The mismatch meant bg-[hsl(var(--muted))] classes
resolved to an invalid color and rendered transparent — most
visible on the Allgemein settings tab where language and week-start
buttons had no background.

Mechanical prefix across ~30 files. Two semantic renames:
- --destructive → --color-error (Mana uses "error" as the token name)
- --popover     → --color-card  (no popover token; card is the closest)

With shared packages on the correct naming, drop the shadcn-compat
alias shim from app.css.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/mana/apps/web/src/app.css

@@ -13,26 +13,6 @@
 @layer base {
 	:root {
 		color-scheme: light dark;
-
-		/* shadcn-compat aliases — some shared-ui components (GlobalSettingsSection,
-		   a few auth-ui pieces) use bare `--muted`, `--primary`, etc. instead of
-		   the `--color-*` tokens this app standardized on. Bridge them here so
-		   `bg-[hsl(var(--muted))]` and friends resolve to a real color. */
-		--primary: var(--color-primary);
-		--primary-foreground: var(--color-primary-foreground);
-		--secondary: var(--color-secondary);
-		--secondary-foreground: var(--color-secondary-foreground);
-		--background: var(--color-background);
-		--foreground: var(--color-foreground);
-		--muted: var(--color-muted);
-		--muted-foreground: var(--color-muted-foreground);
-		--border: var(--color-border);
-		--card: var(--color-card);
-		--card-foreground: var(--color-card-foreground);
-		--accent: var(--color-accent);
-		--accent-foreground: var(--color-accent-foreground);
-		--input: var(--color-input);
-		--ring: var(--color-ring);
 	}
 
 	h1 {