feat(server): INGEST_WING_ROUTING wires the Router; remove the classifier path (#208)

Removes the LLM classifier, the substring 'BM25' scorer, the agreement gate,
the backtest and the old migrate/wingmigrate tooling: measured at 2 of 55
pages placed (#208), and the migration was built for the per-wing facts layout
this branch replaces. wing now holds the decision types, the Router and
KnownWings. INGEST_WING_ROUTING=1 builds the Router (default wing
INGEST_DEFAULT_WING=web-clip, client pattern from INGEST_CLIENT_BLOCK or
CLAUDE_INGEST_CLIENT_BLOCK); a bad default or pattern is fatal at startup.
Watcher tests rewritten for the Router, including a deliberate subfolder into
any existing wing, typo'd folders parked, forged-key and edit-while-placing
cases.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

ingestion/internal/wing/helpers_test.go

@@ -0,0 +1,16 @@
+package wing_test
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func writePage(t *testing.T, dir, rel, body string) {
+	t.Helper()
+	full := filepath.Join(dir, rel)
+	require.NoError(t, os.MkdirAll(filepath.Dir(full), 0o755))
+	require.NoError(t, os.WriteFile(full, []byte(body), 0o644))
+}