Refine Teams overviews, shared conversations and scoped deletion

[ZeroPoint95]

🆕 All teams and chat teams

What changed

Teams now provides a dedicated overview and management surface: nested team cards, faithful conversation previews, paged interactions, actionable questions, and an optional global manager. Recent interactions has persistent Prev and Next controls for paging in both directions through six-row pages. Active manager, member and Global manager cards show a working spinner that stops for questions and idle work, with static marks for ASCII and screen-reader views. Nested children stack in one column with parent labels, counts, and branch guides. Deeper or narrow hierarchies switch to expandable tree rows so descendants remain reachable without shrinking boxes indefinitely.

Chats meanwhile uses one synchronized team overlay selector and a fixed All button for the complete saved conversation library, including conversations without open tabs. A selected team appears as a chip: its name reopens the dropdown and its independent x restores ordinary Chats, synchronizing Teams to All teams. The dropdown lists actual teams only, without a None option.

Team creation uses a searchable Name/Project multi-select picker on Teams and card selection on Chats; both share the same catalog and creation flow. Membership removal preserves conversations and work.

Disbanding recursively ends coordination while retaining history; team deletion removes metadata but preserves conversations. Conversations can be deleted outright.

Conversation deletion stops work and removes its tasks, while task deletion removes only its containment subtree. Ordinary managers must be reassigned in Teams before conversation deletion, and one conversation cannot newly manage unrelated teams.

Final adversarial review repaired stale membership admission after conversation deletion, offline task dependency handling, clipboard routing, narrow layouts and navigation between independently scrolled panes. Manuals and the design record describe the final behavior.

How it was checked

• make pr-ready: build, vet, formatting, packed manuals, retrieval gates, repository laws, and fresh tests for every changed package.
• Focused -race -count=1 regressions across internal/tui3, internal/session, internal/enginehost, internal/teams, and internal/plandb, including deletion, alias tombstones, memberships, overlays, previews and layout.
• make build produces the canonical bin/codeaf; isolated terminal smoke checks use throwaway demo data without the owner's profile or live model requests.
• Adversarial implementation reviews and follow-up review of their revisions. The clear-chip revision passed BASE=15a877c5c make pr-ready, including all eight TUI shards, plus an isolated terminal check of clearing, switching, synchronization and the unchanged All grid.

Checklist

• A feature-level change entry is included (1750-teams-ux-cleanup.md).
• The manual describes the changed controls, routing, capabilities, limits and refusals.
• No known-red exemptions added.
• Only explicit feature paths staged.

Draft for owner review; no merge is requested.

[ZeroPoint95]

converting to draft for now so we can implement a couple additional changes after team review