fix(v3): don't inject empty webhooks: {} for OpenAPI 3.0 docs with a same-named scalar value

[asadtariq96]

What

extractWebhooks (in datamodel/low/v3/create_document.go) called low.ExtractMap[*PathItem](ctx, WebhooksLabel, root, idx) unconditionally and then guarded on the returned key/value nodes (if hooksN != nil && hooksL != nil).

When a document has no top-level webhooks key, ExtractMap resolves the label through the index and can match a same-named scalar value elsewhere in the document — e.g. the webhooks in x-foo: { service: webhooks }, or a server URL ending in /webhooks. That returns a non-nil empty map plus non-nil key/value nodes, so doc.Webhooks gets populated with an empty map, which the high-level model renders as webhooks: {}.

webhooks is an OpenAPI 3.1+ field, so emitting it into a rendered 3.0.x document produces output that fails strict 3.0 schema validation (e.g. Spectral oas3-schema).

Fix

Gate extraction on the genuine top-level webhooks node (nodes.webhooks, already collected by collectDocumentTopLevelNodes), mirroring extractServers / extractTags / extractPaths, which all resolve the real top-level key and guard on vn != nil. extractWebhooks was the only top-level extractor bypassing that.

Regression range

Bisected to cda65e2 ("more model refactoring and cleanup"), first released in v0.35.1. v0.34.4 and earlier are unaffected; v0.35.1–v0.37.3 are affected.

Test

Added TestCreateDocument_WebHooks_NoFalsePositive covering a 3.0 doc whose only occurrence of webhooks is a vendor-extension scalar value; asserts doc.Webhooks is not populated. Existing webhooks tests (TestCreateDocument_WebHooks, TestCreateDocument_WebHooks_Error, the collectDocumentTopLevelNodes tests) still pass, and the full go test ./... suite is green.

Fixes #586

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.72%. Comparing base (ef151b6) to head (acbc61c).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #587   +/-   ##
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  Coverage   99.72%   99.72%           
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  Files         280      280           
  Lines       33894    33896    +2     
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+ Hits        33802    33804    +2     
  Misses         55       55           
  Partials       37       37           

Flag	Coverage Δ
unittests	99.72% <100.00%> (+<0.01%)	⬆️

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[daveshanley]

lgtm, thanks.