feat(web): replace Coming Soon with full marketing landing page #4092

feat: add full document suite — AlecRae Docs (editor, spreadsheet, presentations, templates, collaboration)

feat: add 10 killer features — coach, follow-ups, workflows, sentiment, split-view, notifications, links, timeline, style switcher, network graph

feat: add 10 killer dashboard features with dark theme and onboarding

feat: complete landing page redesign with bold, fun visual identity