feat(v2): subtle inspector entry + tabbed content (drop chevron)

[lilyshen0722]

Summary

The third column had two problems on the YC demo path:

1. Entry was a chevron in the corner — read like "settings panel" not "this is your team."
2. When expanded it dumped 5 stacked sections (Now / Overview / People & Agents / Direct Threads / Resources / Settings) all visible at once — felt like a control surface, not an at-a-glance roster.

Two changes addressing both:

1. Entry redesign — drop the chevron entirely. The chat-header avatar group (already shows the top 3 members + "+N more") becomes the click target. Click to reveal the inspector, click again to hide. Active state is a subtle accent-tinted pill on the avatar group — no chevron, no explicit label, just affordance. When collapsed, the inspector is not rendered at all (no thin sliver column) and chat extends full-width.

2. Tabbed content — three tabs at the top: People (default) · Activity · Settings. Pod overview always pinned to the inspector header above the tabs (it's the "what is this pod" anchor).

   • People — team roster (agents + DM affordance), the demo-relevant view.
   • Activity — Now (recent heartbeat) + Direct Threads.
   • Settings — Resources + add/edit/delete chips.

Tab choice persists in localStorage (`v2.inspectorTab`).

Layout-side cleanup: `V2Layout` decides whether to mount the inspector (only when expanded), passes `onToggleInspector` down to `V2PodChat`, and drops the now-dead `v2-shell--inspector-collapsed` modifier in favor of the existing `v2-shell--no-inspector` 3-column grid. Obsolete chevron CSS (`.v2-inspector__toggle*`, `.v2-pane--inspector-collapsed`) removed.

Test plan

• Open `/v2/pods/` — chat extends full-width by default, no chevron column.
• Click the chat-header avatar group — inspector slides into view with the People tab active. Avatar pill turns accent-tinted.
• Click the avatar group again — inspector hides, chat extends back. Tab choice remembered.
• Click Activity / Settings — content swaps cleanly, no scrollbars from old card stack.
• Click the × in the inspector header — same as clicking the avatar group: hides inspector.
• Refresh the page after picking a non-People tab — tab is remembered.
• No regression on Plan/Execute toggle, Invite button, or pod chat scroll behavior.

🤖 Generated with Claude Code

[lilyshen0722]

Squashed locally and pushed to main. See merge pattern in CLAUDE memory.