Step indicators don't update from install.sh progress markers

[letstakeabreak]

Problem

The install progress screen shows four steps (ESP-IDF, Toolchain, Template,
Scripts), but the circles never fill in during installation.

Suspected Cause

updateSteps(for:) matches install.sh output against markers like "[1/4]".
Possible reasons for failure:

• ESP-IDF "already installed" path skips the [1/4] echo
• Output buffering delivers chunks that split the marker
• Marker string mismatch

Possible Solutions

• Verify exact marker strings echoed by install.sh
• Buffer output by line before matching
• Make matching more robust (line-based, not chunk-based)

Severity

Medium — core value of the installer (visible progress) is reduced.