fix: align package headers with top-level items in task selector

[branchseer]

Summary

Adds consistent indentation to package group headers in the interactive task selector so they align with top-level task items.

Before

  › build:           echo build app
    lint:            echo lint app
  lib (packages/lib)
      build:         echo build lib

The header lib (packages/lib) was indented only 2 spaces, misaligned with the 4-space task items above it.

After

  › build:           echo build app
    lint:            echo lint app
    lib (packages/lib)
      build:         echo build lib

Headers now use 4 spaces, matching the top-level item prefix width.

Test plan

• Unit tests updated and passing (cargo test -p vite_select)
• E2E snapshots updated and passing (cargo test -p vite_task_bin --test e2e_snapshots -- task-select)

🤖 Generated with Claude Code

[branchseer]

• fix: align package headers with top-level items in task selector #220 👈 (View in Graphite)
• main

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