fix(tui): span the vertical tab pulse across the rail - #50836

Issue for this PR

Closes #50426

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

With tabs.layout: "vertical", the running pulse and the separator strips above and below a tab were clipped to a hardcoded 10 columns. On a wide rail that reads as a short stray stripe instead of spanning the tab.

VerticalSessionTabs passed width={indicatorWidth} (10) to every TabPulse. The horizontal layout passes no width, so it gets TabPulse's default "100%". This removes the constant and the four width props so the vertical rail spans its tab the same way the horizontal layout already does. Nothing else changes.

How did you verify your code works?

New test vertical rail pulse spans the tab instead of a fixed 10 columns renders the vertical rail at width 24 with a running tab and checks where the separator row's spans start. Before the change the starts are [0, 3, 6, 10, 24] — the pulse stops at column 10. After, the row reaches the rail edge without a 10-column boundary.

bun test test/component/session-tabs-rail.test.tsx test/component/session-tabs-status.test.tsx \
  test/component/session-tabs-mouse.test.tsx test/component/session-tabs-marquee.test.ts \
  test/component/tab-pulse.test.tsx    # 20 pass, 0 fail
bun typecheck                          # packages/tui, clean
bun run lint                           # clean

The test only relies on span boundaries, not colors, so it is not sensitive to the theme or animation frame.

Screenshots / recordings

A text recording of TUI escape output is not meaningful here; the test captures the rendered span layout and the before/after boundaries are listed above.

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR