Replaces the Metrics ComingSoon placeholder with a form for declaring
metrics (name, message_match_regex, param matchers) and a list/detail
view of declared metrics whose bucket values refetch on selection or
active-range change (no continuous polling, since declare's backfill
already resolves synchronously with the POST).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XFUNZwCvz3kcod3352ZR2o
Extend GET /api/logs to derive each declared param's value per log line
(regex + capture group + kind, matching that line's text) and include it as
a params map on LogEntryDto, omitting entries that don't match rather than
sending nulls. Add GET /api/params (list_params, mirroring list_metrics) so
the frontend can discover currently-declared param names. In LogPreview, add
a column-picker popover backed by that list, with the selection persisted in
localStorage under `ottyl.logPreview.visibleParamColumns`.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XFUNZwCvz3kcod3352ZR2o
