feat: add marketplace phase2 vector retrieval backend

[TheShigure7]

No description provided.

[fennoai]

Found 3 issues worth addressing before this lands.

[codecov]

Codecov Report

❌ Patch coverage is 66.82464% with 490 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
pkg/marketregistry/embedding_jobs.go	62.18%	103 Missing and 60 partials ⚠️
pkg/marketregistry/store.go	62.06%	85 Missing and 47 partials ⚠️
pkg/marketregistry/server.go	52.94%	48 Missing and 8 partials ⚠️
pkg/marketregistry/vector.go	49.38%	37 Missing and 4 partials ⚠️
pkg/marketregistry/search_lexical.go	83.79%	24 Missing and 5 partials ⚠️
pkg/marketregistry/metrics.go	65.38%	18 Missing and 9 partials ⚠️
cmd/anyclaw-registry/main.go	74.00%	12 Missing and 1 partial ⚠️
pkg/marketplace/types.go	0.00%	10 Missing ⚠️
pkg/capability/markettools/marketplace.go	81.08%	5 Missing and 2 partials ⚠️
pkg/marketplace/registry/convert.go	86.00%	5 Missing and 2 partials ⚠️
... and 2 more

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