time_real used uninitialized in Lagrangian bubble output

[sbryngelson]

Bug

In `src/post_process/m_data_output.fpp`, `time_real` is declared as a local variable but never assigned from `file_time` (the value read from the data file). It is then used in output file headers.

File: `src/post_process/m_data_output.fpp` (two subroutines)

Impact: Time stamps in post-processed output files contain uninitialized garbage instead of the actual simulation time.

Severity: High — output metadata contains wrong time values.

[sbryngelson]

Fix: #1190