feat: add edit multi-repo paths dialog (p key)

[oryaacov]

Summary

• Multi-repo sessions currently have no way to add/remove repos after creation — you must delete and recreate
• This adds a new p hotkey that opens an edit dialog for multi-repo sessions, allowing path changes in-place with automatic session restart

Changes

New file: internal/ui/editpaths_dialog.go (578 lines)

• EditPathsDialog modal for editing paths of an existing multi-repo session
• Path list with add (a), remove (d), edit (Enter), navigate (j/k)
• Tab completion via GetDirectoryCompletions (same as new session dialog)
• Floating suggestions dropdown with overlay rendering and ^N/^P cycling
• Validation: min 2 paths, no duplicates, all paths must exist
• ANSI-aware overlay helpers (overlayDropdown, truncateVisible, sliceVisibleFrom) for z-index style dropdown rendering

internal/ui/home.go

• p hotkey opens the dialog when a multi-repo session is focused
• handleEditPathsDialogKey dispatches Enter/Esc to the dialog
• applyMultiRepoPathChanges rebuilds the symlink directory and restarts the session
• p: Paths hint added to bottom status bar, stopped/error Actions sections, and preview pane Multi-Repo section

internal/ui/hotkeys.go: Registered edit_paths action bound to p (customizable)

internal/ui/help.go: Added "Edit multi-repo paths" to help overlay

How it works

1. User presses p on a multi-repo session
2. Dialog shows current paths (resolved from symlinks back to real paths)
3. User adds/removes/edits paths, confirms with Enter
4. applyMultiRepoPathChanges: clears all symlinks in the session's temp dir, creates new symlinks for updated paths, updates ProjectPath/AdditionalPaths, saves to SQLite, calls Restart() (which does respawn-pane with updated --add-dir flags for Claude)

Test plan

• All existing UI tests pass (47+ tests)
• Clean build on main
• Manual: create multi-repo session with 2 repos, press p, add a 3rd repo, confirm → session restarts with 3 repos
• Manual: edit paths dialog shows path suggestions dropdown
• Manual: remove a repo (must keep ≥2), confirm → session restarts with updated repos
• Manual: verify p key is only active on multi-repo sessions (no-op on single-repo)
• Manual: verify bottom bar shows "Paths" hint only for multi-repo sessions

🤖 Generated with Claude Code

[asheshgoplani]

Thanks for the multi-repo paths dialog, @oryaacov! A few issues:

1. Duplicate overlay code with #449 — PR #449 (which introduced the shared overlay pattern) is now merged. This PR still has its own copy of the overlay code. Please rebase onto main and use the shared overlay infrastructure from #449.
2. Race condition in applyMultiRepoPathChanges — this function mutates instance fields (ProjectPaths, etc.) without holding the instance mutex. Since the background status worker also reads these fields, this is a data race under -race. Wrap mutations in inst.mu.Lock()/Unlock().
3. No tests for EditPathsDialog — the new dialog needs test coverage for: adding paths, removing paths, reordering, and the apply/cancel flows.

[oryaacov]

@asheshgoplani , my pleasure, thank you for creating this amazing project!
updated my PR :)