docs: update spectrum-ts documentation for v1.17.1

[photon-action-bot]

Documentation Update: spectrum-ts v1.17.1

This PR updates documentation for spectrum-ts based on the v1.17.1 release.

Release Notes

Breaking Changes

• Removed the no-op webhookSecret option from Fusor webhook setup. Fusor does not sign outbound POSTs, so provider-level verify() remains the source of webhook authenticity.

Bug Fixes

• Fixed Node ESM imports for the published package when bundled CommonJS dependencies call require, avoiding errors like Dynamic require of "x" is not supported.

Improvement

• Added a Node smoke-import check to build and prepack so broken ESM bundles are caught before release. ✨
• Raw Fusor webhook headers are now optional; passing them still works, but Spectrum no longer reads them for an unused outer signature check.

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Version: 1.17.1

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🤖 This PR was auto-generated by Claude Code via the update-docs action in buildspace.

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