sentinel: accept multiple --client-filter values in multicast publisher worker

[snormore]

Summary of Changes

• Make the sentinel multicast publisher worker's --client-filter flag repeatable, so multiple validator client names can be matched in a single run
• Match semantics already used by the admin CLI (controlplane/doublezero-admin): a validator matches if its software client substring-contains any of the given filter names (case-insensitive OR)
• Changes client_filter: Option<String> → client_filters: Vec<String>; flag name --client-filter is unchanged, so existing single-value invocations continue to work

Diff Breakdown

Category	Files	Lines (+/-)	Net
Core logic	2	+19 / -9	+10
Scaffolding	1	+2 / -2	0
Tests	1	+69 / -11	+58
Docs	1	+2 / -0	+2
Total	4	+92 / -22	+70

Small change — the bulk of additions is a new test covering the multi-filter OR semantics.

Key files (click to expand)

• crates/sentinel/src/multicast_publisher.rs — filter predicate now OR-matches against Vec<String>; constructor signatures updated; new multiple_client_filters_match_any test
• crates/sentinel/src/settings.rs — --client-filter declared as Vec<String> (repeatable)
• crates/sentinel/src/main.rs — wiring update for the renamed field

Testing Verification

• All 46 sentinel crate unit tests pass, including the new multiple_client_filters_match_any test that verifies OR semantics and case-insensitive matching across multiple filter values
• Existing single-filter test client_filter_only_creates_for_matching_validators still passes, confirming backward compatibility of the --client-filter foo form