feat: implement governance web interface, SDK, and E2E tests

[Agbasimere]

This pull request implements the complete governance web interface for the Linkora platform. It extends the TypeScript SDK with smart contract governance bindings, creates mock-supported Next.js API route handlers, integrates frontend page routes (for both apps/web and packages/web), and writes E2E Playwright verification tests.

Proposed Changes

1. SDK Extensions (packages/sdk)

• types.ts: Added TypeScript interfaces for GovParameter, GovStatus, GovProposal, and GovConfig.
• client.ts: Implemented govGetConfig(), govGetProposal(), govPropose(), govVote(), govExecute(), and govVeto() calling the smart contract functions using XDR envelope serialization.

2. Next.js Route Handlers (apps/web)

• config/route.ts: Serves contract configuration parameters with a mock fallback.
• proposals/route.ts: Manages in-memory storage of active and historical proposals, supporting POST actions for creations, votes weight adjustments, and veto actions.

3. Frontend Governance Interfaces

• apps/web/src/app/governance/page.tsx: Fully functional governance dashboard styled with Tailwind CSS. Integrates the Freighter wallet connection and LinkoraClient.
• packages/web/app/governance/page.tsx: Inline/CSS variable-styled dashboard built for custom mock execution inside headless E2E testing environments.
• Integrated Views & Validations:
  • Active Proposals listing with time remaining and voting counts.
  • Range validations on form inputs (e.g. FeeBps [0-10000], GovQuorum [1-100], TipCooldownWindow > 0, valid Stellar address for Treasury).
  • Visual quorum indicators representing decay-aware quorum progress.
  • Executed history records.
  • Veto actions (admin-only).

4. Navigation Links

• Added Governance links to navigation headers in:
  • apps/web/src/components/NavBar.tsx
  • packages/web/app/layout.tsx
  • packages/web/app/components/Navbar.tsx

5. Automated Playwright E2E Tests

• Created governance.spec.ts verifying active proposals, input range validations, voting weight count updates, and proposal submissions.

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Verification Plan

1. SDK builds and tests:

pnpm --filter linkora-sdk build
pnpm --filter linkora-sdk test

Closes #597 

[vercel]

@Agbasimere is attempting to deploy a commit to the Jaja's projects Team on Vercel.

A member of the Team first needs to authorize it.

[devJaja]

Resolve the conflict

Fix the fontend E2E CI check

[Agbasimere]

@devJaja Please kindly review.

[devJaja]

@Agbasimere CI checks still failing.
your PR should also include the issue number is clossing