feat: add routes-d billing, wallet, payout, and close endpoints

[HasToBeJames]

Description

Add the missing routes-d endpoints for billing plan lookup, wallet pending balances, payout method defaulting, and account closure with a reason.

Closes #1046
Closes #1027
Closes #1034
Closes #1047

Changes proposed

What were you told to do?

Implement the four routes-d issues in one PR, using the documented paths, auth/ownership checks, structured errors, and unit tests.

What did I do?

Billing and wallet endpoints

• Added GET /api/routes-d/billing/plan to return the authenticated user's active subscription summary.
• Added GET /api/routes-d/wallet/pending to return pending invoice totals for the authenticated wallet owner.

Default payout method and account close

• Added PATCH /api/routes-d/payout-methods/[id]/default to promote a payout method and clear the previous default.
• Added POST /api/routes-d/account/close to create a pending account closure request with a reason and grace window.

Verification

• Added route tests for the happy path and key failure cases for all four endpoints.
• Verified the touched files with ESLint and the new vitest suite.
• Verified the touched files are clean under TypeScript's no-emit check.

Check List (Check all the applicable boxes)

• My code follows the code style of this project.
• This PR does not contain plagiarized content.
• The title and description of the PR is clear and explains the approach.
• I am making a pull request against the main branch (left side).
• My commit messages styles matches our requested structure.
• My code additions will fail neither code linting checks nor unit test.
• I am only making changes to files I was requested to.

Screenshots / Testing Evidence

• node node_modules\\eslint\\bin\\eslint.js passed for the touched route files and tests.
• npx vitest run tests/api.routes-d.billing-plan.test.ts tests/api.routes-d.wallet-pending.test.ts tests/api.routes-d.payout-methods.default.test.ts tests/api.routes-d.account-close.test.ts passed: 4 files, 16 tests.
• node node_modules\\typescript\\bin\\tsc --noEmit reported no errors in the touched files.

[vercel]

@HasToBeJames is attempting to deploy a commit to the david's projects Team on Vercel.

A member of the Team first needs to authorize it.

[drips-wave]

@HasToBeJames Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

Learn more about application limits

[HasToBeJames]

Superseded by #1088 which contains the same work. Closing this duplicate.