Fix incorrect I/O log base offsets in logsrvd

[Z-Bra0]

logsrvd generates relative log IDs using the length of iolog_base, derived from the configured directory. Path expansion can shorten that directory by collapsing %%, collapsing repeated leading slashes, or removing trailing slashes. This mismatch can produce an incorrect relative path or an out-of-bounds read during log-ID generation.

Stop the base at a directory boundary before the first % escape and normalize its leading and trailing slashes consistently with path expansion. Keep expanded components in the relative log ID so reconnects reconstruct the correct path.

Add regression coverage for literal percent escapes, date and named escapes, repeated slashes, and root directories. Tests verify base extraction, offset bounds, and reconnect path reconstruction.