feat(desktop): View all multi-agent activity panel in channels

[DevvGwardo]

Summary

When multiple agents are working in a channel, the composer activity bar exposes a View all control that opens a right-side auxiliary panel of live activity cards. Each card embeds the same compact session transcript used by the single-agent activity pane, pinned to the latest rows, and drills into the full feed via View.

• View all appears when 2+ agents are actively working (composer row + multi-agent popover)
• Panel lists working agents only (idle harnesses stay out)
• Cards reuse ManagedAgentSessionPanel with compactPreview so tool/message rows match the individual activity look
• Shared headline clamping (clampHeadline) prevents shell/tool dumps from exploding overview UIs
• Auxiliary body padding preserves the single-panel top inset so the first card header is not covered

Test plan

• With 2+ managed agents working in a channel, confirm View all appears next to the inline activity bar
• Click View all → right panel opens with one card per working agent (no idle rows)
• Each card shows recent transcript activity (latest tools/messages), not early session setup
• Card header (avatar / name / View) is fully visible under the panel title
• View opens that agent's full activity panel
• Panel closes on Escape / close affordance; channel switch dismisses panel
• Single-agent path unchanged (no View all when only one agent working)

Closes #2915 (reopened as fresh PR — DCO now passing, rebased on main)

[DevvGwardo]

Maintainer note (branch refresh)

• Rebased onto latest main (was 49 commits behind; clean rebase).
• Fixed a wiring bug: ChannelPane used onOpenAllAgentsActivity / onCloseAllAgentsActivity / allAgentsActivityOpen without destructuring them from props, so View all could not actually open the panel. Typecheck is clean after the fix.
• Unit tests for botActivityViewAll still pass (5/5).
• DCO sign-off retained on all commits.

Still helpful for review: UI screenshots / short recording of View all with 2+ working agents (per CONTRIBUTING).

[DevvGwardo]

Perf pass (pushed)

• View all cards skip SQLite archive hydration (includeArchivedEvents={false}) so N working agents do not each page archive history
• Lazy-mount card transcripts via IntersectionObserver (offscreen cards stay cheap)
• Compact preview caps live items/blocks and disables framer motion for multi-agent overview
• Faster working-set scans in botActivityViewAll / composer activity bar

Still on branch tip: perf(desktop): lighten multi-agent View all activity panel

[DevvGwardo]

This is still DIRTY against main (conflicts in ChannelPane.tsx, ChannelPane.types.ts, ChannelScreen.tsx, AgentSessionTranscriptList.tsx, channels.spec.ts).

I started a rebase onto current block/buzz main; it dies on commit 2 (fix(desktop): broaden View all agent activity visibility) inside ChannelPane.tsx. Not force-pushing a half-resolved ChannelPane — that file has moved a lot on main since Aug 3.

To land: rebase feat/show-all-agent-activity onto origin/main, re-wire the View-all panel into the current ChannelPane props/types, and re-run the desktop channel e2e. Until then this cannot merge.

[DevvGwardo]

Closing this. It is still conflicting with main (ChannelPane and related files moved since Aug 3) and is not worth a half-rebase. A fresh PR can pick this up later if the View-all activity panel is still wanted.