fix: preserve MCP session lifecycle across sequential tool calls

[leonam13]

Summary

This solves this issue: #3142

• keep MCP tool executions in persistent Maestro sessions by reusing session instances when closeOnCompletion is disabled
• preserve one-shot CLI behavior by retaining explicit close-and-cleanup on completion for default session mode
• harden cleanup flow to avoid masking primary command failures when close operations fail

Test plan

• ./gradlew :maestro-cli:compileKotlin
• Run MCP flow twice in same server process (e.g. launch_app then run_flow) and verify no repeated driver reinstall
• Restart MCP server and verify first call initializes a fresh session as expected

[simon-gilmurray]

Had a test of this @leonam13 and it still seemed to be failing after a while for me - also then running CLI separately afterwards still had an error launching app too - have you tested this out?

[leonam13]

@simon-gilmurray there are two different issues. When running MCP and then running CLI, the latter will drop the former. I've been experiencing this issue and the workaround was to avoid using CLI while the MCP session is on.

For a pure MCP test, this did it work for me, the agent was able to launch and stop the app multiple times, only invoking the launch app tool.