feat: Agent display name across remaining surfaces — operator, monitoring, executions, graph (#964 follow-up 5/5)

[vybe]

Summary

Apply the display name to the remaining surfaces: operator queue, monitoring, executions, the collaboration graph, tab titles, and prose/toast strings. Lowest value per site and safely deferrable — until this lands these surfaces keep showing the slug, which is correct behavior, just not the polished version.

Follow-up 5 of 5 from the design decision on #964.

Context

Per the #964 render rule, these split across three surface classes:

• Dense operational tables (machine-facing) — the slug stays primary; the display name is supplementary at most. Executions rows, operator queue rows, monitoring alerts, and RoleMatrix (a 100px column header — extremely tight).
• Prose / toasts (identity already established) — display name alone reads better than a concat.
• Collaboration graph — needs a store change before it can show anything.

Most of these components read agent_name out of API payloads, not the agents store, so the backend payloads need the field or the frontend needs a slug→display resolver. That decision is the main design work in this issue.

Acceptance Criteria

• Decision recorded: add display_name to operator/monitoring/executions payloads, or build a frontend slug→display resolver from the agents store (with the tradeoff stated)
• Dense operational tables keep the slug primary per the spike: Support a friendly display name on agents separate from the slug-based name #964 render rule:
  • src/frontend/src/components/ExecutionsPanel.vue table rows
  • src/frontend/src/components/operator/ — QueueCard, QueueList, QueueItemDetail, ResolvedCard, NotificationsPanel
  • src/frontend/src/components/MonitoringPanel.vue alert + health rows
  • src/frontend/src/components/process/RoleMatrix.vue (100px column — slug only)
  • src/frontend/src/views/MobileAdmin.vue ops rows
• Collaboration graph shows the display name without breaking actions:
  • Sibling field added in src/frontend/src/stores/network.js (both the agent and system-agent node data)
  • data.label remains the slug — it is the API key for router.push / toggleAutonomy / toggleAgentRunning in AgentNode.vue
• Prose / toast strings use the display name alone — Agents.vue notifications, Settings.vue confirms, PortalChat.vue empty state, PortalFilesPanel.vue headings
• Router tab titles in src/frontend/src/router/index.js resolve the display name via a store lookup (they currently derive from the route param, so they only ever have the slug) — or an explicit decision to keep slug-only there
• Remaining :title= / :alt= / aria-label strings reviewed — accessibility labels should carry the display name where it aids comprehension
• ReplayTimeline.vue, FoldersPanel.vue, ExecutionDetail.vue breadcrumb + source-agent attribution, PermissionsPanel.vue, TerminalPanelContent.vue, AgentWorkspace.vue, AgentBrainOrb.vue reviewed against the render rule
• AgentAvatar still receives the slug everywhere (including the duplicate initials/tint implementation in ClientPortal.vue)

Technical Notes

Comment in src/frontend/src/router/index.js explicitly calls :name "the canonical agent identifier" — that stays true; only the rendered title changes.

ReplayTimeline.vue and the operator cards already render an avatar beside the name, so they have marginally more room than a bare table cell — worth a case-by-case call rather than a blanket rule.

Comma-joined agent lists (e.g. the GitHub PAT propagation failure list in Settings.vue) get unreadable fast with long display names — slug is probably right there.

Depends on: the #964 schema/API/MCP issue. Independent of the roomy-surfaces and pickers issues; can land last or in parallel.