Move common third-party resolver to thirdparty pkg

resolveOrCreateCommonThirdParty lived as a package-level helper in the
tracker mapping worker, but the common pattern enrichment worker now
reuses it. Homing shared catalog logic in a mapping-named file made the
enrichment worker quietly depend on the mapping worker's file, and it is
not a mapping concern.

Move it to pkg/thirdparty as exported ResolveOrCreateCommonThirdParty,
decoupled from cookiebanner's TrackerMappingAgentResult (it now takes a
name and category) to avoid an import cycle. It stays a transaction-
scoped free function so both workers compose it into their own tx for
atomicity rather than receiving a service that owns its own connection.

Relocate the catalog dedup DB test alongside it.

Signed-off-by: Émile Ré <emile@probo.com>

pkg/thirdparty/resolver.go

@@ -0,0 +1,94 @@
+// Copyright (c) 2026 Probo Inc <hello@getprobo.com>.
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+package thirdparty
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"go.gearno.de/kit/log"
+	"go.gearno.de/kit/pg"
+	"go.probo.inc/probo/pkg/coredata"
+	"go.probo.inc/probo/pkg/gid"
+	"go.probo.inc/probo/pkg/slug"
+)
+
+// ResolveOrCreateCommonThirdParty links a named vendor to the global
+// catalog, creating a row when none matches. Dedup is deterministic:
+// exact name, then slug, before insert. Callers run inside their own
+// transaction and pass the logger explicitly, so it is shared by the
+// tracker mapping worker (which supplies observed domains) and the
+// common pattern enrichment worker (which has none).
+func ResolveOrCreateCommonThirdParty(
+	ctx context.Context,
+	tx pg.Tx,
+	logger *log.Logger,
+	name string,
+	category coredata.ThirdPartyCategory,
+	domains []string,
+) (*gid.GID, error) {
+	var party coredata.CommonThirdParty
+	if err := party.LoadByName(ctx, tx, name); err == nil {
+		return &party.ID, nil
+	}
+
+	partySlug := slug.Make(name)
+	if partySlug == "" {
+		return nil, nil
+	}
+
+	if err := party.LoadBySlug(ctx, tx, partySlug); err == nil {
+		return &party.ID, nil
+	}
+
+	now := time.Now()
+	party = coredata.CommonThirdParty{
+		ID:             gid.New(gid.NilTenant, coredata.CommonThirdPartyEntityType),
+		Name:           name,
+		Slug:           partySlug,
+		Category:       category,
+		Certifications: []string{},
+		CreatedAt:      now,
+		UpdatedAt:      now,
+	}
+
+	if err := party.Insert(ctx, tx); err != nil {
+		return nil, fmt.Errorf("cannot create common third party: %w", err)
+	}
+
+	for _, domain := range domains {
+		domainRecord := coredata.CommonThirdPartyDomain{
+			ID:                 gid.New(gid.NilTenant, coredata.CommonThirdPartyDomainEntityType),
+			CommonThirdPartyID: party.ID,
+			Domain:             domain,
+			CreatedAt:          now,
+			UpdatedAt:          now,
+		}
+
+		if _, err := domainRecord.Upsert(ctx, tx); err != nil {
+			return nil, fmt.Errorf("cannot create common third party domain: %w", err)
+		}
+	}
+
+	logger.InfoCtx(
+		ctx,
+		"created common third party from agent identification",
+		log.String("name", name),
+		log.String("category", category.String()),
+	)
+
+	return &party.ID, nil
+}