fix(ingest): route raw claude-session dumps to non-indexed archive, not wiki

claudeSink wrote every raw transcript into brain/wiki/claude-sessions/facts/
(BM25-indexed), duplicating what ai-sessions' curated summaries already
cover and out-ranking them in search (177,818 vs 45,335 BM25 weight on the
same query, per ai-sessions#10 investigation). Raw dumps now land in
brain/archive/claude-sessions/<host>/ — kept for deep lookups, never
indexed, never deleted.

Refs: ai-sessions#10

ingestion/cmd/server/main_test.go

@@ -14,7 +14,7 @@ import (
 	"github.com/mathiasbq/hyperguild/ingestion/internal/claudewatcher"
 )
 
-func TestClaudeSink_IngestTagsSourceTypeInternal(t *testing.T) {
+func TestClaudeSink_IngestWritesToNonIndexedArchiveNotWiki(t *testing.T) {
 	dir := t.TempDir()
 	sink := &claudeSink{brainDir: dir, logger: slog.New(slog.NewTextHandler(os.Stderr, nil))}
 
@@ -29,8 +29,10 @@ func TestClaudeSink_IngestTagsSourceTypeInternal(t *testing.T) {
 	})
 	require.NoError(t, err)
 
-	got, err := os.ReadFile(filepath.Join(dir, "wiki", "claude-sessions", "facts", "session-koala-abc.md"))
-	require.NoError(t, err)
-	assert.Contains(t, string(got), "source_type: internal")
-	assert.Contains(t, string(got), "wing: claude-sessions")
+	got, err := os.ReadFile(filepath.Join(dir, "archive", "claude-sessions", "koala", "session-koala-abc.md"))
+	require.NoError(t, err, "raw session dump must land in the non-indexed archive")
+	assert.Contains(t, string(got), "did a thing")
+
+	_, err = os.Stat(filepath.Join(dir, "wiki", "claude-sessions"))
+	assert.True(t, os.IsNotExist(err), "raw transcripts must never land under wiki/ (ai-sessions#10 — BM25 pollution)")
 }