[Projects] Humanoid page: link to Learning Projects (related platforms)

[andrewy1n]

Problem

Humanoid.tsx does not point visitors to feeder platforms on /projects/learning-projects, so the narrative from testbeds → flagship humanoid is easy to miss.

Scope

• Add a small secondary block: short copy + link to Learning Projects explaining how Pupper, arms, teleop/VLA, and mobile testbeds support humanoid development (tone per club voice).
• Keep it visually subordinate to the main humanoid story (no competing hero).

Acceptance Criteria

• Link target is /projects/learning-projects (or the canonical route used in App.tsx).
• Uses Typography + existing layout patterns; lint/typecheck pass.

Files

• src/pages/Projects/Humanoid.tsx

Priority

Suggest P2 — polish after Learning Projects page content is updated (#168 / #169 / #170).