feat(dsh-plugin): better-sidebar 集成、会话关停与归档清理、悬浮窗修复 (#130)

* better-sidebar 集成：observation 视图迁入 better-sidebar 载体，按会话作用域展示 bsk 会话
* 会话关停与归档清理：支持会话 dispose 与归档自动清理
* 悬浮窗修复：悬浮 overlay 拖拽/缩放/PiP 弹出等问题修复
* 修复 Document PiP 空白窗口：载体卸载（关 tab、切会话、插件 HMR）时主动 close() PiP 窗口，避免残留空白窗口

packages/dsh-plugin-browserskill/src/sessions.ts

@@ -24,6 +24,13 @@ export interface TrackedSession {
 export class SessionRegistry {
   private readonly sessions = new Map<string, TrackedSession>();
   private currentId: string | undefined;
+  /**
+   * bsk session id → the DSH session ids that may clean it up: the agent
+   * session that started it plus every ancestor along the seed lineage, so
+   * archiving a conversation at ANY level of the chain reaps its browsers
+   * (see archive-cleanup.ts).
+   */
+  private readonly dshOwners = new Map<string, ReadonlySet<string>>();
   /**
    * Slots reserved by in-flight starts. reserveStart/completeStart/abandonStart
    * run synchronously around the async spawn, so concurrent starts can never
@@ -72,12 +79,37 @@ export class SessionRegistry {
   /** Forget a session; falls back to the most recent remaining one. */
   remove(sessionId: string): void {
     this.sessions.delete(sessionId);
+    this.dshOwners.delete(sessionId);
     if (this.currentId === sessionId) {
       const rest = [...this.sessions.values()];
       this.currentId = rest.length > 0 ? rest[rest.length - 1].sessionId : undefined;
     }
   }
 
+  /**
+   * Record which DSH conversation(s) a freshly started bsk session belongs
+   * to (the starting agent's session plus its ancestors). No-op without ids
+   * — e.g. a start whose caller carried no agent identity.
+   */
+  trackOwner(sessionId: string, dshSessionIds: readonly string[]): void {
+    if (dshSessionIds.length === 0 || !this.sessions.has(sessionId)) return;
+    this.dshOwners.set(sessionId, new Set(dshSessionIds));
+  }
+
+  /** bsk session ids owned by the given DSH conversation (or its descendants). */
+  ownedByDsh(dshSessionId: string): string[] {
+    const owned: string[] = [];
+    for (const [sessionId, owners] of this.dshOwners) {
+      if (owners.has(dshSessionId)) owned.push(sessionId);
+    }
+    return owned;
+  }
+
+  /** The DSH conversation ids owning one bsk session (empty when untracked). */
+  dshOwnersOf(sessionId: string): string[] {
+    return [...(this.dshOwners.get(sessionId) ?? [])];
+  }
+
   /** Mark an owned session as most recently used (recency order refresh). */
   private touch(sessionId: string): void {
     const existing = this.sessions.get(sessionId);