Feature: Normalize Home discovery surfaces (EPIC-3.8)

[masvelio]

Summary

Normalize HomePage and CommunityHomePage by extracting shared discovery sections and reducing page-local orchestration.

Problem / Motivation

HomePage and CommunityHomePage now sit on the path of newer discovery UI, including contest and prediction-market surfaces. The plan explicitly calls for normalizing the home surfaces and extracting shared discovery sections before EPIC-4.15 migrates Explore/Home/dashboard-related areas.

Proposed Solution

• Reduce page-local orchestration in HomePage and CommunityHomePage.
• Extract shared discovery sections that should not remain embedded in individual home pages.
• Keep prediction-market discovery surfaces in scope, especially ActivePredictionMarketList and related home-facing modules.
• Preserve current home/community-home route behavior and user-facing layout logic.

Acceptance Criteria

• Shared discovery sections are extracted from the current home surfaces where appropriate.
• HomePage and CommunityHomePage have clearer ownership boundaries and less embedded section logic.
• Prediction-market and contest discovery UI continues to render correctly after the refactor.
• The resulting structure is ready for EPIC-4.15 migration work.
• Build/typecheck and relevant component/E2E checks pass.

Alternatives Considered

• Defer all home-surface cleanup to EPIC-4.15. This was rejected because new discovery UI is already increasing coupling inside the legacy pages.
• Split only one of the two home surfaces. This was rejected because the plan explicitly treats them as paired work around shared discovery ownership.

Impact

This reduces duplication across home surfaces, keeps discovery UI from spreading further through legacy pages, and lowers risk for the later Explore/Home migration wave.

Links

• Plan doc: common_knowledge/Commonwealth-Frontend-Refactor-Plan.md
• Milestone: https://github.com/hicommonwealth/commonwealth/milestone/136?closed=1

Additional Context

The latest audit puts CommunityHomePage.tsx at 211 lines and HomePage.tsx at 74 lines, but the main risk is not raw size alone. The bigger issue is that shared discovery sections and newer prediction-market surfaces are still owned by legacy page shells.