feat(issues): live agent activity chip + per-issue indicator + filter (#3058)

* feat(server): broadcast task:running event

The dispatched → running transition was silent: only task:queued,
task:dispatch, task:cancelled, task:completed and task:failed
broadcast over WS. Any UI that distinguishes "queued" from "running"
(e.g. the new issue-card agent activity indicator) would lag by up to
the 30s agentTaskSnapshot staleTime on the most user-visible
transition. StartTask now broadcasts task:running so the workspace
snapshot invalidates immediately, keeping the agent activity UI live.

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

* feat(issues): live agent activity chip + per-issue indicator + filter

Surfaces "which agents are working on what, right now" in the Issues
and My Issues views, with a one-click filter to narrow the list to
issues that have a running agent task.

Two visual surfaces:

- **Workspace chip** in the header (left of Filter). Shows the
  brand-tinted avatar stack of agents currently running on visible
  issues. Click toggles a page-scoped filter; idle state renders a
  static "0 working" button with a hover-card placeholder. When the
  filter is active the chip pins to brand fill across hover and popover
  states (the Button outline variant otherwise repaints back to
  neutral). A muted "Viewing only working agents" hint sits to the
  left of the chip whenever the filter is on, so users notice the
  active state without having to hover.

- **Per-issue indicator** on every board card and list row (top-right
  of the identifier line). Renders the avatar stack of agents in
  running or queued state on that issue, full-opacity ring at brand/70
  when ≥1 is running, half-opacity stack when only queued. Returns
  null when nothing is in flight.

Both surfaces open the same hover-card body that lists each active
task with the agent avatar, status dot (composed via the existing
availability + workload tokens), and a live-ticking duration.

Adds a new "All" scope to /my-issues that unions assignee, creator,
and involves_user_id via three parallel fetches deduped on the
client — no backend changes for this part. The chip's count and the
quick-filter both use the page's currently visible issue ids so they
stay in sync with the active scope.

State is per-user (Zustand + localStorage) and the agentRunningFilter
is intentionally omitted from partialize — running state changes
second-to-second and a stored toggle would land users in an
unexplained empty list. WS task:running, already added in the
preceding commit, drives real-time updates without polling.

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

* refactor(issues): swap indicator ring pulse for shimmer text label

Earlier iterations layered a brand ring with various opacity-pulse
cadences around the per-issue avatar stack. Every tuning attempt was
either invisible (transparent ring + faded pulse) or oppressive (a
visible ring that flashed on a dense board). Moves the "alive" signal
onto a small text label and reuses chat's existing
`animate-chat-text-shimmer` utility — a soft light sweep across the
glyphs that already powers the ChatGPT-style "thinking" cue in
task-status-pill.

Indicator now reads as a 12 px avatar stack + 10 px label:

- Running → full-opacity avatars + shimmering localized "Working"
- Queued  → half-opacity avatars + muted static "Queued"
- Idle    → render nothing (unchanged)

Avatars and the surrounding card stay completely still; only the few
glyphs animate. The label is i18n-driven via the existing
`status_running` / `status_queued` keys, so no locale changes are
required.

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

---------

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

server/pkg/protocol/events.go

@@ -32,6 +32,7 @@ const (
 	// change" — not "every internal status flip".
 	EventTaskQueued    = "task:queued"    // ∅ → queued (enqueue / retry create)
 	EventTaskDispatch  = "task:dispatch"  // queued → dispatched (daemon claim)
+	EventTaskRunning   = "task:running"   // dispatched → running (daemon started)
 	EventTaskProgress  = "task:progress"
 	EventTaskCompleted = "task:completed" // running → completed
 	EventTaskFailed    = "task:failed"    // running → failed