Harden the seams a project sweep surfaced

A systematic review of the whole codebase (main process, renderer,
IPC/migration/packaging seams) surfaced four real defects; each is
fixed at its root:

- Legacy catalogue drift: the operator's profile still carried 89
  active skills from the removed ~/.agents import era next to the 228
  built-ins. Catalogue sync now mirrors the bundle - actives whose slug
  the bundle does not ship retire (bindings keep resolving via their
  pinned revisions; retired skills leave list_skills and cannot be
  granted anew)
- Broken-bundle guard: staging now refuses a bundle without the
  humanizer skill, so an empty or quarantined resources folder can
  never trigger the mirror pass into retiring a healthy catalogue
- Duplicate agent names: @mentions, DM routing, and task assignment all
  resolve by name, so createAgent and updateAgent renames now reject a
  name already held by an active agent (case-insensitive); the mention
  resolver still refuses to guess between legacy duplicates
- Stale DM titles: agent-to-agent conversation rows titled themselves
  from the frozen creation-time space name, so renames never reached
  the sidebar; direct titles now derive from members' current names

Verified clean in the same sweep: IPC surface (82 channels, handler +
preload + api aligned), per-migration transactions with rollback,
quota-parking month rollover, retry-budget counting, meeting spot
reuse across floor-plan rebuilds.

src/renderer/src/pages/chat/chat-helpers.ts

@@ -127,12 +127,16 @@ export function buildConversations(input: {
   const items = input.spaces.map((space) => {
     const last = lastBySpace.get(space.id) ?? null;
     const isDirect = space.spaceType === "direct";
-    const counterpart = isDirect
-      ? resolveCounterpart(membersBySpace.get(space.id) ?? [], input)
-      : null;
+    const members = membersBySpace.get(space.id) ?? [];
+    const counterpart = isDirect ? resolveCounterpart(members, input) : null;
+    // Direct titles derive from the members' CURRENT names — the space name
+    // froze whatever they were called when the conversation was created, so
+    // renames would otherwise never reach the sidebar.
+    const liveNames = isDirect ? resolveMemberNames(members, input) : [];
+    const directTitle = counterpart?.name ?? (liveNames.length > 0 ? liveNames.join(" · ") : space.name);
     return {
       space,
-      title: isDirect && counterpart ? counterpart.name : space.name,
+      title: isDirect ? directTitle : space.name,
       isDirect,
       counterpart,
       preview: last ? `${senderName(last, context)}: ${previewText(last)}` : null,
@@ -143,6 +147,20 @@ export function buildConversations(input: {
   return items.sort((a, b) => b.lastActivityAt.localeCompare(a.lastActivityAt));
 }
 
+/** Current display names of a space's members, in membership order. */
+function resolveMemberNames(
+  members: ChatMembershipRecord[],
+  input: { employees: EmployeeRecord[]; agents: AgentRecord[] },
+): string[] {
+  return members
+    .map((member) => {
+      if (member.principalType === "agent") return input.agents.find((item) => item.id === member.principalId)?.name ?? null;
+      if (member.principalType === "employee") return input.employees.find((item) => item.id === member.principalId)?.displayName ?? null;
+      return null;
+    })
+    .filter((name): name is string => name !== null);
+}
+
 /**
  * The single other party of a direct conversation, from the viewer's seat.
  * Conversations between two agents have no single counterpart for the