Phase 2: forum shell (nav, footer, components)

[CalebisGross]

Part of #339

Build the forum chrome that wraps all pages:

• css/nav.css — top bar (vBulletin gradient), sticky navbar with tabs, breadcrumbs
• css/components.css — forum rows, blocks, type icons (IN/DE/LE/ER), tags, buttons, quote blocks
• css/drawer.css — activity drawer restyled
• js/components.js — renderForumRow(), renderForumBlock(), renderColumnHeader(), renderTypeBadge(), renderBreadcrumb(), renderToast()
• Footer status bar (version, memory counts, encoding status, consolidation time)
• Remove Mind tab from navigation
• Keyboard shortcuts renumbered (1-6)

[CalebisGross]

Completed on feat/dashboard-phase-0 branch. See commit history for details.