fix(midnight-sdk): route Midnight API defaults to v0

[prd-carapulse]

Summary

• Switch the Midnight API default base URL from https://api.morpho.org/v1/midnight to https://api.morpho.org/v0/midnight.
• Update API tests to assert every default Books, quote, takeable-offer, and mempool validation route uses /v0/midnight.
• Update JSDoc, TIB docs, and the pending Midnight SDK changeset so examples/docs point at the v0 route.

Test Plan

• RED: updated MidnightApi route tests to expect /v0/midnight; observed failures while production still used /v1/midnight.
• pnpm --filter @morpho-org/midnight-sdk test --run
• pnpm --filter @morpho-org/midnight-sdk build
• pnpm lint:ci
• git diff --check
• Independent pre-commit reviewer passed: no security concerns, no logic errors.

Request Context

• Initiator: Romain / Slack: <@U03L0SC1JUR> / GitHub: unresolved
• Initial Slack thread: channel C0B3LEQJQDA, thread 1782396593.698139
• Additional context: User requested migrating v1 routes to v0 on the Midnight API in midnight-sdk, in code and examples.
• Rationale: Keep the SDK default route and public examples aligned with the current Midnight API version.

Requested by: <@U03L0SC1JUR>

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[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no potential bugs to report.

View in Devin Review to see 1 additional finding.