feat(client): add dispute open/resolve UI

[LamsOfJos]

Summary

Adds the missing UI for opening and resolving campaign disputes — previously the only path was calling open_dispute/resolve_dispute on the contract directly, even though both hooks already existed in useEscrowMutations.ts.

Closes #145

What was implemented

• Open dispute: new OpenDisputeForm component using the existing useOpenDispute() hook, wired into CampaignDetailPage. Visible only when the connected wallet is the campaign's farmer, a contributing investor (useContribution > 0), or the escrow admin (useEscrowAdmin) — mirroring the contract's own .require_auth() boundary as a UX convenience, not the authorization boundary itself.
• Resolve dispute: CampaignAdminPanel.tsx already had a ResolveDisputeForm wired to useResolveDispute(), covering all three resolution types (FullRefund / FullPayout / PartialSettlement), with the payout-amount field only required for PartialSettlement. Verified this satisfies the admin-side acceptance criterion as-is — no changes needed there.

Notes / scope

• CampaignDetailPage still renders local mock campaign state (a separate, already-tracked gap — "once Issue 1 makes it real"). Added a farmer field to its mock CampaignData and kept OpenDisputeForm fully prop-driven so it drops in unchanged once the page is wired to real contract data.
• An accessibility pass on the new UI (the issue's last checkbox) is not included here — recommend a follow-up once the component is exercised against real campaign data.

Testing

• Added 7 tests in OpenDisputeForm.test.tsx (client/src/components/campaign/tests/), following the existing CampaignAdminPanel.test.tsx mocking pattern: wallet-not-connected, ineligible wallet (renders nothing), farmer/contributor/admin success paths, empty-reason validation, and contract-rejection error surfacing.
• tsc -b, eslint, prettier, and vite build all pass for the changed/new files.
• Full client suite: 68/70 passing. The 2 failures are in ActivityFeed.test.tsx, confirmed pre-existing on master via git stash — unrelated to this change.
• Known pre-existing issue, not introduced here: npm run lint / npm run format:check currently fail repo-wide (~90 prettier errors in ActivityFeed.tsx, ActivityFeedItem.tsx, activityLabels.ts, registry.test.ts, ActivityFeedPage.tsx) — none of these files are touched by this PR, and the failures reproduce on a clean master checkout.

Files changed

• client/src/components/campaign/OpenDisputeForm.tsx (new)
• client/src/components/campaign/__tests__/OpenDisputeForm.test.tsx (new)
• client/src/pages/CampaignDetailPage.tsx

[shinzoxD]

@LamsOfJos leaving #188 / #189 for after this PR. I mistakenly opened overlapping PRs that re-added OpenDisputeForm and closed them (#215, #216).