feat(ui): show merged-into-parent badge on adopted observations

ObservationCard renders a secondary "merged → <parent>" chip when
merged_into_project is set, next to the existing project label.
Both are meaningful: project is origin provenance, merged_into_project
is the current home.

Extends PaginationHelper's observations and summaries queries with
OR merged_into_project = ? so the single-project viewer fetch pulls
in adopted rows — the plan's Phase 3 covered multi-project context
injection; this is the single-project UI read path.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/services/worker-types.ts

@@ -124,6 +124,7 @@ export interface Observation {
   id: number;
   memory_session_id: string;  // Renamed from sdk_session_id
   project: string;
+  merged_into_project: string | null;
   platform_source: string;
   type: string;
   title: string;

src/services/worker/PaginationHelper.ts

@@ -80,6 +80,7 @@ export class PaginationHelper {
         o.id,
         o.memory_session_id,
         o.project,
+        o.merged_into_project,
         COALESCE(s.platform_source, 'claude') as platform_source,
         o.type,
         o.title,
@@ -100,8 +101,10 @@ export class PaginationHelper {
     const conditions: string[] = [];
 
     if (project) {
-      conditions.push('o.project = ?');
-      params.push(project);
+      // Include adopted merged-worktree rows so the parent project's view
+      // surfaces observations that originated under its merged children.
+      conditions.push('(o.project = ? OR o.merged_into_project = ?)');
+      params.push(project, project);
     }
     if (platformSource) {
       conditions.push(`COALESCE(s.platform_source, 'claude') = ?`);
@@ -156,8 +159,10 @@ export class PaginationHelper {
     const conditions: string[] = [];
 
     if (project) {
-      conditions.push('ss.project = ?');
-      params.push(project);
+      // Include adopted merged-worktree summaries so the parent project's view
+      // surfaces rows that originated under its merged children.
+      conditions.push('(ss.project = ? OR ss.merged_into_project = ?)');
+      params.push(project, project);
     }
 
     if (platformSource) {