fix(web-ui): keep worktree sessions in their owning project

[kev1n77]

Summary

A session that runs in a managed Git worktree was addressed with the worktree's own workspace record everywhere. That record is created on demand for execution and is normally not an open workspace, so the session dropped out of the project's session list as soon as its first message materialized the worktree, returning to it reported that its workspace was not open, and session storage, session state and composer configuration requests were rejected by the host.

This PR gives session-to-workspace identity one shared owner and splits the two facts that were previously conflated:

• Owning project ID (sessionOwningWorkspaceId) drives navigation group membership, session storage, session state, archive/rename/compact/fork/delete/export, the usage report, and the session's own configuration catalogs.
• Execution ID (the worktree workspace record) keeps driving where the work runs: session creation, turn dispatch, git state, the workspace strip, and terminal cwd.

It also marks such a row with a worktree badge, lets the worktree directory be opened as its own workspace from the row menu, and keeps the two workspaces' session lists separate.

Type and Areas

Type: bug fix (session ownership/regression fix) with a small UI/UX change.

Areas: Web UI only - NavPanel sessions and workspaces sections, flow_chat session store/services/drivers/utilities, terminal and scene-activation hooks, shared i18n locales (en-US, zh-CN, zh-TW). No Rust change and no persisted-format change.

Motivation / Impact

Reported behavior:

• Creating a session from the composer's local menu with a new worktree made the session disappear from the current workspace and attached it to the worktree directory instead.
• Re-entering that session reported "the workspace this session belongs to is not open yet; reopen that workspace before switching to this session".
• The composer could not resolve modes, subagents, or external sources, and restore_session_view / load_session_turns / save_session_turn / delete_session failed for the session while the run itself worked.
• Terminals opened for the session ran in the project directory, so a hand-started shell used the main working tree while the agent edited the worktree.
• The session row's worktree marker carried a text label, the new menu entry copy was long enough to fade under the menu's overflow mask, and a linked worktree row showed a "show more +N" affordance for rows it could never reveal.

What changes for users:

• A worktree-isolated session stays in the session list of the workspace it was created from, and is marked with an icon-only worktree badge whose tooltip carries the execution directory.
• The worktree directory can be opened as its own workspace; it shows its own sessions and does not list the project's sessions.
• Terminals created for that session start in the execution (worktree) root. An explicit directory, such as the file explorer's "open terminal here", still wins.
• Session storage and configuration now resolve for these sessions instead of failing.

Verification

Automated:

• pnpm --dir src/web-ui run type-check - pass.
• pnpm --dir src/web-ui exec eslint <changed source files> - pass (0 errors; test files are excluded by the eslint config).
• pnpm --dir src/web-ui run test:run src/app/components/NavPanel - 33 files / 198 tests pass.
• pnpm --dir src/web-ui run test:run src/app/components/NavPanel/sections/sessions src/app/hooks/useSessionTerminalDirectory.test.ts src/app/hooks/sessionTerminalDirectoryWiring.test.ts src/flow_chat/utils/sessionOrdering.test.ts src/flow_chat/utils/sessionWorktree.test.ts src/flow_chat/store/FlowChatStore.test.ts src/app/scenes/terminal/TerminalActionBridge.test.tsx - 16 files / 247 tests pass.
• pnpm run i18n:audit - pass, 0 warnings (locales updated; the now unused nav.sessions.worktreeBadge key removed from all three catalogs).
• pnpm run theme:color-audit:all - pass, 23 surfaces.

Manual, Windows desktop (local workspace), run by the reporter:

• Open a project folder, create a session, choose "New worktree" in the composer's local menu: the session stays in that project's list, with the worktree badge and the worktree path in its tooltip.
• Run a turn: the agent works in the worktree directory; a new terminal for the session opens there.
• Open the worktree directory as its own workspace: it lists its own sessions only.
• Re-enter the worktree session after restarting: it activates its owning project and no longer reports an unopened workspace.
• A linked worktree row no longer shows an empty "show more +N".

Not exercised: remote workspace, Remote Control, Peer Device Mode and Detached Dispatch paths. The change is frontend identity routing, and this branch was verified against a local workspace only.

Reviewer Notes

Ownership rules this PR relies on (see src/web-ui/src/flow_chat/utils/sessionOrdering.ts):

• A session whose config.executionTarget.kind !== 'local' is worktree-isolated and is owned by projectWorkspaceId, falling back to the execution ID.
• Every other session is owned by the workspace it was created in - including a session created while browsing a linked worktree as its own workspace, which stays under that worktree row even though the worktree's project ID points at the main checkout.
• Top-level IDs are authoritative; config copies only serve legacy records persisted without them. Legacy records with no workspace identity stay unresolved rather than being grouped by a guessed folder.

Trade-off accepted for the expand toggle: for a linked worktree row, the storage-level metadata total counts the project's sessions (both resolve to the same session directory), so the toggle is now sized from the rows that row actually owns. A worktree's own session that falls beyond the loaded page of that storage domain is therefore not revealed by "show more" - this is the pre-existing storage-domain paging versus navigation-domain filtering mismatch, and the row is now at least not offering rows it cannot show.

Compatibility: no persisted field was added, removed, or repurposed, and no migration or data repair is needed. Rollback is a plain revert of the branch.

Rebase note: this branch was rebased onto 3756f38c1, where upstream removed the in-row __inline-item-cron-badge in favor of the trailing scheduledJobMark; the worktree badge was re-inserted between the dispatch and review badges accordingly.

Checklist

• This PR is focused and does not include secrets, temporary prompts, generated scratch files, or unrelated artifacts.
• Relevant verification is recorded above, or skipped checks are explained.
• User-facing strings, docs, and locales are updated where applicable.