Execute Project Runs With App Reuse

[drown0315]

Parent

#98

What to build

Implement Project Run orchestration across discovery, launch, hot restart,
Scenario execution, artifacts, and final status. A Project Run should launch the
Target App Package once, run the first Scenario directly, hot restart before
later Scenarios, continue after Scenario execution failures, stop on
environment-level failures, and produce the correct Project Run status and exit
code.

Acceptance criteria

• Project Run launches the Target App Package once.
• The first Scenario runs without a preliminary hot restart.
• Later Scenarios run after a hot restart.
• Flutter Pilot hot restarts after a failed Scenario before continuing.
• Scenario execution failure records that Scenario's artifacts and does not stop later Scenarios.
• Launch failure, Target Device resolution failure, Project Scenario validation failure, discovery failure, and hot restart failure stop the Project Run.
• Project Run exits 0 only when every Scenario passes.
• Project Run exits 1 when one or more Scenario Runs fail.
• Tests use fake launch, fake hot restart, and fake runner boundaries.
• Tests cover launch reuse, continuation after Scenario failure, stop on hot restart failure, Project Run report status, and final exit code.

Blocked by

• Discover Project Scenarios #99
• Hot Restart Launched Target App #100
• Group Project Run Artifacts #102