chore: drop legacy context module files (companion to acb737e25)

Companion deletion sweep — acb737e25 removed all the *registry refs*
to the legacy `context` module, but its source files were still on
disk on main (because the original deletion in d3e2e73ca on the
articles-bulk-import branch was bundled with unrelated photon /
broadcast-rename work and never landed on main). Dropping them now
so the consolidation is self-contained:

- apps/mana/apps/web/src/lib/modules/context/ — entire module dir
- apps/mana/apps/web/src/routes/(app)/context/ — page routes
- apps/mana/apps/web/src/lib/components/dashboard/widgets/ContextDocsWidget.svelte
- apps/mana/apps/web/src/lib/i18n/locales/context/{de,en,es,fr,it}.json
- packages/shared-branding/src/logos/ContextLogo.svelte

Verified: svelte-check + tsc --noEmit both clean.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/shared-branding/src/logos/ContextLogo.svelte

@@ -1,13 +0,0 @@
-<script lang="ts">
-	import AppLogo from '../AppLogo.svelte';
-
-	interface Props {
-		size?: number;
-		color?: string;
-		class?: string;
-	}
-
-	let { size = 55, color, class: className = '' }: Props = $props();
-</script>
-
-<AppLogo app="context" {size} {color} class={className} />