Session sidebar: ⌘K search with wildcard/regex, and per-repo subtabs

[jbachorik]

The sidebar listed every repository as one flat TreeView. With more than a handful of repos that became unreadable, and the global filter shortcut (⌘F) collided with the conventional in-terminal find binding. This change restructures the sidebar around per-repository subtabs and upgrades the search shortcut and matcher.

Session search: ⌘K + wildcard/regex

The global "focus the sidebar filter" shortcut moves from ⌘F to ⌘K (ShortcutsOverlay relabelled "Session search"), freeing ⌘F for a future terminal-find binding.

The filter's text matcher is extracted into SidebarQuery, which adds two shapes on top of the historical case-insensitive substring:

• Glob — */?, other regex metacharacters escaped.
• Regex — /body/ or re:body, compiled CASE_INSENSITIVE|DOTALL with find().

An unparseable regex body falls back to a literal substring match of the body, never throwing — a typo in the filter must not blank the sidebar. RepositorySidebar compiles the matcher once at the top of rebuildTree; matchesRepo/matchesNode/matchesPullRequest and the PR-group narrower all consult it instead of a lowercased substring.

Per-repo subtabs instead of a flat tree

The flat all-repos TreeView is replaced by a wrapping FlowPane strip of per-repository ToggleButtons above the TreeView, which now shows only the selected repo's subtree. One repo is visible at a time; the subtab titles wrap inside a bounded width (long repo names take as many rows as they need) and the strip itself wraps across rows as the sidebar narrows.

A subtab is shown iff the repo name matches the text filter OR any of its session/worktree rows do — the same filter the old flat treeview used, now deciding subtab visibility instead of expand-and-keep. Within a shown repo, rows filter exactly as before (chips AND text, facets OR within an axis).

The repo pane keeps everything the expandable row carried (sessions, unopened worktrees, stale/locked buckets, the PULL REQUESTS group, the ⟳ rescan and the + new-session button); the repo row is now an always-expanded pane header (caret and click-to-collapse removed, a force-re-expand guard defeats keyboard ←). Per-repo collapse state (collapsed/collapsedBeforeFilter/filterChangedSinceLastRebuild) is gone — there is nothing to collapse.

Selecting a subtab replaces the old "repo-row expand" as the lazy PR-scan trigger, and refreshWorktrees's collapsed-skip became a not-selected-skip (isSelectedRepo): a repo whose worktree list changes while nobody is looking at it is marked stale and self-heals the moment its subtab is reselected. Switching the active session to another repo auto-selects that repo's subtab so its subtree is the one showing when the row is revealed.

Verification

• ./gradlew :app:test --tests "app.drydock.ui.*" — all green, including the rewritten dedup FX test.
• The dedup FX test's "collapsed self-heals on expand" case is rewritten to the subtab model ("deselected self-heals on reselect"), driving the worktree rescan through the workspace seam (refreshWorktreesFor) since the ⟳ button lives on the repo row a deselected repo does not show.
• Not covered: manual visual verification of the subtab strip layout (wrapping, multi-row titles) against a real multi-repo workspace — the FX tests exercise the behaviour, not the CSS layout.

Out of scope

5 unrelated git worktree add timeouts in GitStatusServiceTest/WorkspaceMcpSessionContextTest reproduce on clean main (verified by stashing this branch); they are caused by the global core.hooksPath secrets-scanner hook under parallel load, not by these changes.