Implement the approved APES theme and responsive component system

[bmurphy-apescic]

Parent issue

Tracks #13.

Summary

Implement the approved Option 1 Gecko Guide visual direction across the shared APES public website theme while preserving the current PHP-first architecture, route map, primary logo, and Cloudron LAMP hosting model.

Scope

• Extend shared semantic colour, typography, spacing, radius, elevation, and layout tokens.
• Rework the shared header, navigation, hero, primary actions, route finder, content surfaces, footer, responsive behaviour, and branded error-page chrome.
• Preserve the approved APES teal, mint, warm sand, and restrained coral palette.
• Keep the homepage focused on finding help, adoption, and supporting APES.
• Ensure the component system works across existing page templates rather than introducing page-owned styling.

Non-scope

• Route or service-eligibility changes.
• Primary logo redesign.
• Mascot interaction logic or dark-mode persistence, which have separate child issues.
• Deployment.

Acceptance criteria

• The shared homepage and internal-page layouts are recognisably aligned with the approved Option 1 mock-up.
• Header, hero, route finder, content surfaces, footer, and error-page chrome remain usable at desktop, tablet, and mobile widths.
• Existing public routes, canonical behaviour, navigation destinations, footer requirements, and APES Newsroom routing remain unchanged.
• Shared CSS remains modular and sourced from public/theme/.
• Focus states, readable typography, touch targets, and content hierarchy meet accessibility expectations.
• Chatwoot, donation widget, development notice, navigation, and sticky header do not overlap.
• PHP rendering, generated static output, and Cloudron LAMP compatibility remain intact.

Validation

• PHP lint and repository validation.
• Local HTTP preview of homepage, representative internal routes, and branded errors.
• Desktop, tablet, and mobile browser checks.
• Footer, navigation, Newsroom, SEO, and sitemap regression checks.

Progress updates

Post updates for branch creation, meaningful layout milestones, validation results, blockers, and readiness for review. Include Files changed whenever repository files have changed.

[linear-code]

WEBDEV-37