Unify campaign/investor pages on soil/leaf tokens and wire CampaignDetailPage to :id

[matthewrball]

Summary

• Two incompatible design systems are mixed across the app #148 Unify the investor/campaign pages off the leftover slate/emerald palette onto the shared soil / leaf / status-* tokens. Campaign detail uses <StatusBadge>; investor stats use <StatTile>.
• CampaignDetailPage ignores its route param and always renders mock data #186 CampaignDetailPage now reads :id from the route (useParams + useCampaign) instead of always rendering mock camp-101. Routes: /campaigns, /campaigns/new, /campaigns/:id.
• New test: client/src/pages/__tests__/CampaignDetailPage.test.tsx.

Closes #148
Closes #186

Notes

• Shared Card/Button CSS modules are still the old slate HSL system. These pages use Tailwind tokens directly so they match Header/StatTile.
• Pre-existing on master (not in this PR): ActivityFeed.test.tsx failures and an ImportMeta tsc error in ActivityFeedPage.
• GrantFox Third Campaign listing: Maybe Rewarded / not escrowed. Happy to apply/assign if that's the preferred claim path.

Test plan

• CampaignDetailPage with a real :id loads that campaign (or an error if missing)
• /campaigns and /campaigns/new still resolve
• Investor dashboard + investment cards use soil/leaf tokens, not slate/emerald
• Status badges and fund CTA match Header/StatTile contrast
• New CampaignDetailPage tests pass