feat: file browser for Import and Export Config - #663

Import and Export Config used to be bare text fields: the full path had
to be typed exactly, pasted paths with quotes failed, relative paths
silently resolved against the launch directory, and export would quietly
mkdir -p the target folder and overwrite any existing file.

Both dialogs now use an arrow-key file browser built on ink-file-picker
(pinned to 0.3.2, bundled like the other dev dependencies).

Import
- Opens in the launch directory and lists folders plus .json files
  (case-insensitive). Enter opens a folder or picks a file; Left /
  Backspace goes up; typing filters.
- Ctrl+T switches to a typed-path bar pre-filled with the current
  folder; a folder path jumps the browser there. Ctrl+O toggles hidden
  files.

Export
- Same browser plus an editable "File name:" field, starting in ~ with
  ccstatusline-config.json. Tab moves between list and name field,
  Ctrl+S saves into the current folder, Enter on an existing .json
  targets it, and Ctrl+T types a full path. ".json" is appended when
  missing; empty names, path separators, NUL bytes and names over 255
  bytes get an inline error.
- Writing is now explicit: an existing file asks "Overwrite it?" (naming
  the real file when the target is a symlink), a missing folder asks
  "Create it and export?", and dangling symlinks, devices and pipes are
  refused. exportConfig takes { createDir, overwrite } and writes with
  the 'wx' flag unless the overwrite was confirmed, so a file that
  appears between the check and the write is never clobbered. A declined
  prompt or any failure returns to the dialog with folder and name kept.

Implementation
- Library patch (patches/[email protected], registered in
  patchedDependencies): the list container had no flexDirection, so Ink
  laid entries out in one truncated row. The patch also makes the focus
  marker configurable, labels the header "Folder:", fixes the
  filter-mode footer text, and types `theme` as partial overrides to
  match the runtime merge.
- src/tui/components/file-picker-common.tsx holds the shared theme
  (green ▶ like the other menus), a [Key] action hint bar matching the
  library footer, the .json filter and path helpers.
- The dialogs only report a chosen path. App resolves it and classifies
  it with the pure helpers in src/utils/export-target.ts, then runs the
  confirm flows. Extra shortcuts use Ctrl combos because the picker
  treats every printable key as type-ahead. Both dialogs guard against
  double submission, and the confirm action ignores a second Yes.
- normalizeImportPath is renamed normalizeUserPath (trim, strip quotes,
  expand ~, resolve) and is used by both directions.

Tests: new ImportConfigDialog, ExportConfigDialog and export-target
suites, plus config tests for path normalization and the new export
options. Lint is clean and the full suite passes.

bun.lock also picks up bun's dedupe of @typescript-eslint 8.67 -> 8.70
(dev-only lint tooling).