fix(current-working-dir): don't count ~ as a segment, and preview every segment count - #685

What

• Home abbreviation with segments: Current Working Dir no longer counts the leading ~ as one of the kept segments. With abbreviate-home on and segments set to 2, ~/Projects/my-project now renders as ~/Projects/my-project instead of ~/.../Projects/my-project, which elided nothing.
• Preview: the TUI preview now shows the segment count that's set. With segments set to 3 it previews .../Documents/Projects/my-project instead of .../example/project.

Why

• ~ counted as a segment: the widget splits the path and elides it when there are more parts than segments. After home abbreviation, ~ is one of those parts:

  cwd	settings	before	after
  ~/a/b	home, segments 2	~/.../a/b	~/a/b
  ~/a	home, segments 1	~/.../a	~/a
  ~/a/b/c	home, segments 2	~/.../b/c	~/.../b/c
  /a/b	segments 2	/a/b	/a/b

  The ~ is always kept in front of the ..., so counting it meant one segment fewer was ever shown in full, and the ... stood for nothing.

• Preview: the preview was a set of fixed strings for one segment and "more than one". Every count from 2 up previewed .../example/project (or ~/.../Projects/my-project with home on), while the status line shows that many segments. The strings also weren't cut from the sample path the preview otherwise shows (/Users/example/Documents/Projects/my-project): one segment previewed .../project.

How

The segment logic moves into a keepLastSegments helper that both the status line and the preview call. It skips a leading ~ part when counting and keeps it in front as before. Everything else works as before: separator detection (/ or \), UNC and leading separators, and paths outside home. Fish style ignores segments, as before. The preview runs the helper over its sample path (/Users/example/Documents/Projects/my-project, or ~/Documents/Projects/my-project with home on), so it shows exactly what the setting does to that path. Previews for one and two segments change too, to segments of the sample path: .../my-project and .../Projects/my-project.

Demo

The TUI preview is its built-in sample path. The status line is piped with sample payloads under a scratch home.

Setting segments to 3 in the TUI:

Powerline: before

Powerline: after

Plain: before

Plain: after

Home abbreviation with segments set to 2, for a directory two levels below home and one three levels below (unchanged):

Powerline: before

Powerline: after

Plain: before

Plain: after

Testing

• New tests, each failing on main first: ~ isn't counted (2 of ~/Projects/my-project, 1 of ~/Projects); the preview at 1 to 5 segments, and at 3 and 4 with home on.
• bun test: 2791 pass, 0 fail. bun run lint passes.
• The changed test file under Node (Vitest) fails as a whole, as it does on main (24 of 24 there, 33 of 33 here). Its beforeEach spies on os.homedir, which Node doesn't allow. So I checked the built CLI instead: under Bun 1.4.2 and Node 26.10.0 with a scratch HOME, ~/Projects/my-project (2) and ~/Projects (1) render without .... ~/Documents/Projects/my-project (2), /a/b and /a/b/c render as on main. Both runtimes agree.
• Built CLI with a Model and Current Working Dir line (home on, 2 segments) and the baseline line, under Bun 1.4.2 and Node 26.10.0: all runtimes agree in plain and Powerline modes, and the output matches main (the payload's cwd isn't under home). The TUI opens and exits cleanly under both.