Refactor launcher connection error logging into internal/launcher

[Copilot]

[LAUNCHER]-prefixed connection failure logs were split across internal/mcp and internal/launcher, which blurred ownership and made launcher log behavior harder to find and evolve. This change consolidates launcher-specific error diagnostics in the launcher package and removes launcher-prefixed behavior from mcp internals.

• Logging ownership realignment

  • Added internal/launcher/connection_error_log.go with:
    • ConnectionErrorContext
    • LogConnectionError
  • This moves all [LAUNCHER] connection-failure formatting and hint logic into the launcher subsystem.

• Launcher call-site update

  • Updated internal/launcher/log_helpers.go:
    • logLaunchError now invokes launcher-local LogConnectionError(...)
    • Removed dependency on mcp.ConnectionErrorContext / mcp.LogConnectionError.

• mcp package decoupling

  • Removed launcher-specific connection error logging implementation from internal/mcp/connection_logging.go.
  • Updated internal/mcp/connection.go connection-failure branch to emit mcp-scoped structured errors (including sanitized stderr) without [LAUNCHER] console conventions.

• Test ownership alignment

  • Moved connection-error logging tests from internal/mcp/errors_test.go to internal/launcher/connection_error_log_test.go so behavior coverage lives with the owning package.

// before (launcher -> mcp)
mcp.LogConnectionError(mcp.ConnectionErrorContext{ ... }, err)

// after (launcher-local ownership)
LogConnectionError(ConnectionErrorContext{ ... }, err)