Promote glob source and trigger draft on adoption

The pattern-analysis worker dropped two signals on every run. When
InsertIfNotExists hit a pre-existing glob, the computed bestSource
was discarded by the LoadByBannerIDTypeAndPattern fallback, so the
SCRIPT > EXTENSION > PRE_EXISTING precedence advertised on
bestSource was only ever enforced at first insert. Subsequent
batches with stronger sources could not promote the glob, even
though the page-script-wins rule already lives in detected_trackers
at the row level.

Separately, adoptUncategorisedPatterns returned an adopted bool
that the worker discarded; the function moves detected trackers
from uncategorised exact patterns into categorised globs, which is
a real consent transition, but no draft banner version was created
on adoption-only runs.

Add a focused TrackerPattern.PromoteSource that only updates the
source and updated_at columns. Express the precedence as a pure-Go
shouldPromoteSource helper alongside bestSource so the rule is
unit-testable without a database. The worker now calls
InsertIfNotExists, then on conflict loads, skips when the slot is
held by an exact pattern or a user-recategorised glob, and only
calls PromoteSource when the candidate source ranks above the
existing one.

The skip branch is now documented: adoptUncategorisedPatterns is
the safety net that re-homes uncategorised exacts into the existing
glob via globMatch. Capture its adopted return value and use it
(instead of the previous over-eager consentChanged flag) to gate
ensureDraftVersionForBanner. Merging exacts into a glob in their
own category never changes visitor consent, so the prior flag
produced redundant draft versions on every non-uncategorised merge.

Cover the new pieces with three test layers: pure-unit cases for
shouldPromoteSource (precedence matrix including HTTP/nil collapse
and equal-rank no-write), DB-backed tests for PromoteSource (touch
only source + updated_at, ErrResourceNotFound for missing rows),
and end-to-end worker tests for source promotion on an existing
glob, draft-on-adoption, and the merge-only no-draft case.

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

pkg/cookiebanner/pattern_analysis_worker_test.go

@@ -1051,3 +1051,103 @@ func TestDurationBucket(t *testing.T) {
 		)
 	}
 }
+
+func TestShouldPromoteSource(t *testing.T) {
+	t.Parallel()
+
+	script := coredata.CookieSourceScript
+	extension := coredata.CookieSourceExtension
+	preExisting := coredata.CookieSourcePreExisting
+	http := coredata.CookieSourceHTTP
+
+	tests := []struct {
+		name      string
+		existing  *coredata.CookieSource
+		candidate *coredata.CookieSource
+		want      bool
+	}{
+		{
+			name:      "nil existing promotes to SCRIPT",
+			existing:  nil,
+			candidate: &script,
+			want:      true,
+		},
+		{
+			name:      "nil existing promotes to EXTENSION",
+			existing:  nil,
+			candidate: &extension,
+			want:      true,
+		},
+		{
+			name:      "nil existing does not promote to PRE_EXISTING (equal rank)",
+			existing:  nil,
+			candidate: &preExisting,
+			want:      false,
+		},
+		{
+			name:      "PRE_EXISTING promotes to SCRIPT",
+			existing:  &preExisting,
+			candidate: &script,
+			want:      true,
+		},
+		{
+			name:      "PRE_EXISTING promotes to EXTENSION",
+			existing:  &preExisting,
+			candidate: &extension,
+			want:      true,
+		},
+		{
+			name:      "EXTENSION promotes to SCRIPT",
+			existing:  &extension,
+			candidate: &script,
+			want:      true,
+		},
+		{
+			name:      "SCRIPT does not promote to PRE_EXISTING",
+			existing:  &script,
+			candidate: &preExisting,
+			want:      false,
+		},
+		{
+			name:      "SCRIPT does not promote to EXTENSION",
+			existing:  &script,
+			candidate: &extension,
+			want:      false,
+		},
+		{
+			name:      "EXTENSION does not promote to PRE_EXISTING",
+			existing:  &extension,
+			candidate: &preExisting,
+			want:      false,
+		},
+		{
+			name:      "SCRIPT does not promote to SCRIPT (equal rank, no write)",
+			existing:  &script,
+			candidate: &script,
+			want:      false,
+		},
+		{
+			name:      "HTTP collapses to PRE_EXISTING rank: does not promote SCRIPT",
+			existing:  &script,
+			candidate: &http,
+			want:      false,
+		},
+		{
+			name:      "HTTP collapses to PRE_EXISTING rank: equal to nil existing",
+			existing:  nil,
+			candidate: &http,
+			want:      false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(
+			tt.name,
+			func(t *testing.T) {
+				t.Parallel()
+
+				assert.Equal(t, tt.want, shouldPromoteSource(tt.existing, tt.candidate))
+			},
+		)
+	}
+}