feat: turn docs into the OpenAMRobot Knowledge Hub

[BotshareAI]

Summary

Transforms the documentation site from a component-oriented technical index into the public OpenAMRobot Knowledge Hub for operators, builders, integrators, developers, entrepreneurs, and partners.

Information architecture

• Adds role-based Start Here entry points
• Implements the robot-ownership journey: Understand → Build → Bring Up → Configure → Train → Use → Maintain → Customize
• Adds Solutions pages for intralogistics, retail, manufacturing, facility/service operations, education/research, and evidence-based pilots
• Adds the entrepreneur journey: Discover → Choose a Model → Validate → Launch → Sell → Deliver → Support → Scale
• Expands Botshare Academy into programs, practical certifications, and the Certified Training Partner path
• Separates public partner recruitment from the planned protected Partner Portal
• Adds a technical-reference landing layer while preserving existing canonical repository pages

Design

• Promotes the Partner Program visual language into a site-wide design system
• Adds rich heroes, status chips, cards, process paths, panels, enhanced tables, blockquotes, and admonitions
• Improves dark-mode and responsive behavior
• Applies stronger global typography and content hierarchy to existing pages without rewriting their technical content

Partner Program

• Adds a clear onboarding path and wider partner-ecosystem context
• Refines partner targeting toward organizations with applied, industry-facing delivery capability

Validation

• python -m mkdocs build --strict passes with the social plugin temporarily disabled locally because its font/social-card generation requires network access; the plugin remains enabled in this PR for CI/production.
• git diff --check passes.
• The repository's existing scripts/check_docs.sh still reports its pre-existing root README.md fenced-block-position error; this PR does not modify that README.