Add plugin row actions and detail tabs; fix disable navigation and mobile sidebar access

[brsbl]

Human comments

What was wrong

• Plugin row menus lacked detail and disable actions, while mobile offered an unsupported split action.
• View details left the current workspace. Disabling an open plugin briefly showed an unavailable panel and left stale navigation history.
• Full-screen mobile panels covered the left sidebar control.

What changed

• Shares the same dropdown and right-click actions: Open in split when supported, View details, Hide from sidebar, separator, Disable. Mobile omits splitting. Hide from sidebar keeps its existing label, eye-off icon, and visibility-only behavior; direct plugin launch is unchanged.
• Opens or focuses details in the current new-thread, thread, or plugin workspace. Close panel tab / Cmd+W closes visible details without terminating the underlying terminal. Detail tabs support reordering alongside existing tabs.
• Keeps early detail requests in their original pane while it loads; discards pending requests when that workspace is replaced.
• Removes only the disabled plugin’s panes before unloading it. Other splits stay open; the last pane becomes New thread. Replaces the active history entry and refreshes installed-plugin state.
• Keeps mobile sidebar access reachable on Plugins, plugin details and workspaces, Settings, and Skills. Uses existing menu and panel primitives; no public SDK, protocol, or persisted-data changes.

How you verified

• Post-merge CI is resolved: all 13 jobs passed on 9882e4a79, including Linux FUSE/AppImage checks.

Post-merge CI failure and resolution

The original merge run on 22c3fc0e8261e84f275c4a16c4f9b9bc9a47b150 passed 12 jobs but timed out twice in the shared Ubuntu FUSE-install step. The preceding main run had the same failure.

The shared workflow fix in #3486, 9882e4a79cbb7f354d73f9cc2e96a700c33f08fb, pins a reachable HTTPS Ubuntu mirror and skips optional DEP-11 metadata. That main revision includes this PR. Its remote CI passed all 13 jobs: FUSE installation completed in six seconds, followed by successful AppImage packaging and mount-lifecycle smoke. Version Lockstep also passed. No additional plugin changes were needed.

• Remote CI is green for 33b2a2b1dda5b0761bdcdbf91933900d6a73307e: all six test shards, build/typecheck/lint, bundle checks, Linux/macOS package smoke on Node 22, and PR guards passed. Node compatibility and mobile E2E were skipped by workflow conditions. No CI-equivalent checks ran locally.
• Regression coverage protects menu parity and compact split omission, hide-versus-disable behavior, disable/history/split preservation, terminal-safe detail closure, tab ordering, loading-time pane ownership, and mobile sidebar controls. The close, reorder, and early-open regressions failed remotely before their fixes.
• User QA passed the broader flows and restored Hide from sidebar menu on 1e95783ec59d583af9d45694f798d435902d1e46; browser/version/viewport were not recorded.
• Exact-head targeted browser QA passed on native Apple Silicon Chrome for Testing 153.0.8010.36 against 33b2a2b1dda5b0761bdcdbf91933900d6a73307e, light theme, desktop 1440×900 and mobile 390×844 with touch, scale 1. Verified the row menus, detail tabs retaining the current workspace, mobile sidebar access, Cmd+W preserving a running underlying terminal, mixed detail-tab reordering, and a detail request made while the plugin workspace module was deliberately held pending. Reused prior valid QA for unchanged disable/split flows. The only browser console message during these checks was the existing Jotai loadable deprecation warning.
• Captured and visually inspected six matched before/after pairs and two additional final-head detail-tab views in the same isolated source-app checkout. Attachments are hosted directly in get-bb/bb, outside product-code commits.

Screenshots

• Before: merge base fa1f44ebe9e5676004b669e48c99b3c7606466b6. After: exact head 33b2a2b1dda5b0761bdcdbf91933900d6a73307e.
• All captures use the branch web app in native Chrome for Testing 153.0.8010.36, light theme, scale 1, and the same isolated synthetic data with first-party Plugin Guide and Automations enabled. Each pair matches route, fixture, interaction, and viewport. Desktop is 1440×900; mobile is 390×844 with touch.
• Row menus: /, Plugin Guide options open; open the sidebar first on mobile. Plugin details: direct /plugins/plugin-api-docs, settled first carousel slide, sidebar closed.
• Retained mobile access: /settings on General, /skills on Browse, and /plugins/automations/automations on Installed with zero automations; each at the top with sidebar closed.

Flow / viewport	Before — merge base	After — final head
Row menu — desktop 1440×900
Row menu — mobile 390×844
Plugin details — mobile 390×844
Settings — mobile 390×844
Skills — mobile 390×844
Plugin workspace — mobile 390×844

• Additional final-head flow: start at /, open Plugin Guide options, select View details, and dismiss the mobile drawer. Details remain in a tab while the new-thread workspace and route are preserved. These are after-only views because the merge-base row menu has no View details action.

After — web/desktop 1440×900	After — mobile 390×844

BB-Thread-ID: thr_ccffp4w2p2

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