Add `loglevel` param propagation across the data feed and sampling
subsystems to enable proper console log setup in downstream (distibuted)
subactor tasks. This ensures sampler and history-mgmt tasks receive the
same loglevel as their parent `.data.feed` tasks.
Deats,
- add `loglevel: str|None` param to `register_with_sampler()`,
`maybe_open_samplerd()`, and `open_sample_stream()`.
- pass `loglevel` through to `get_console_log()` in
`register_with_sampler()` with fallback to actor `loglevel`.
- use `partial()` in `allocate_persistent_feed()` to pass
`loglevel` to `manage_history()` at task-start.
- add `loglevel` param to `manage_history()` with default
`'warning'` and pass through to `open_sample_stream()` from there.
- capture `loglevel` var in `brokers.cli.search()` and pass to
`symbol_search()` call.
Also,
- drop blank lines in fn sigs for consistency with piker style.
- add debug bp in `open_feed()` when `loglevel != 'info'`.
(this commit msg was generated in some part by [`claude-code`][claude-code-gh])
[claude-code-gh]: https://github.com/anthropics/claude-code