feat(watcher): Placer interface; acceptance tests for the sprint goal (#209)

A clip dropped in raw/ with no other action lands in web-clip, its entity and
concept are the shared pages, raw/ is empty and nothing waits for a human;
client-marked text and a typo'd wing name park; a deliberate subfolder places.
Real pipeline and file layout, model stubbed.

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

ingestion/internal/watcher/watcher_wing_test.go

@@ -2,6 +2,7 @@ package watcher
 
 import (
 	"context"
+	"encoding/json"
 	"errors"
 	"os"
 	"path/filepath"
@@ -41,7 +42,7 @@ func wingResolver(c wing.Classifier, s wing.Scorer) *wing.Resolver {
 	}
 }
 
-func wingTestCfg(t *testing.T, r *wing.Resolver, llmCalls *atomic.Int32) (Config, string) {
+func wingTestCfg(t *testing.T, r wing.Placer, llmCalls *atomic.Int32) (Config, string) {
 	t.Helper()
 	brainDir := setupBrainDir(t)
 	return Config{
@@ -329,3 +330,11 @@ func TestWithProposal_ANonFenceDashLineDoesNotCloseTheBlock(t *testing.T) {
 	assert.Contains(t, strings.Join(lines[:closing], "\n"), "proposal_reason:")
 	assert.NotContains(t, strings.Join(lines[:closing], "\n"), "foo: bar", "the unfenced note is body, not part of the block")
 }
+
+func mustJSONPages(pages []pipeline.RawPage) string {
+	b, err := json.Marshal(pages)
+	if err != nil {
+		panic(err)
+	}
+	return string(b)
+}