Add Launch Failure Progress Output

[drown0315]

Parent

#90

What to build

Make Target App Launch Progress fail clearly when the Target App Package cannot
provide a Runtime Target. Startup failures should show a concise failure
summary, elapsed launch time, and the buffered Flutter stderr tail. Default
output should remain bounded and high signal rather than streaming full Flutter
build logs.

The completed slice should preserve the existing launch failure behavior while
making it visible in the same Target App Launch Progress surface users watched
during startup.

Acceptance criteria

• Launch failure output includes a clear Target App launch failure summary.
• Launch failure output includes elapsed launch time.
• Launch failure output includes the buffered Flutter stderr tail when available.
• Launch failure output remains bounded to the existing stderr tail behavior rather than printing full Flutter logs.
• Launch failure output is written to stderr.
• test --json suppresses launch progress output while preserving command failure behavior.
• Tests cover Flutter exiting before Runtime Target availability, stderr tail display, bounded output, and JSON suppression.

Blocked by

• Add Plain Target App Launch Progress #91