Fixes:
- Same-line collision splitting now recognizes log headers that lack the idle
  percentage field (older/eSInet FreeSWITCH cores emit "TIMESTAMP [LEVEL]
  source:line" directly, with no NN.NN%). Two entries concatenated on one
  physical line — e.g. an un-terminated WARNING ("aborting REFER.") followed
  by the next entry's intact header — previously stayed merged, hiding the
  trailing entry from -u filtering and session tracking. The idle percentage
  is now treated as optional, matching the line parser.