sentinel: improve multicast publisher find/create commands

[snormore]

Summary of Changes

• Fix owner bug: multicast publisher users were being created with the sentinel payer as owner instead of the validator's IBRL user owner, causing incorrect PDA derivation for access passes and user accounts
• Add multi-value --client filter to both find and create commands (OR semantics, repeatable flag)
• Add --ip filter to create command for targeting specific validator IPs
• Add "NEAREST DEVICE" column to find output showing the closest DZ device with available multicast publisher capacity (geographic Haversine distance from the validator's current device)
• Re-evaluate target device per-candidate during create execution so slots filled earlier in the run are reflected in subsequent device selection; warn-and-skip if no device has capacity
• Strengthen e2e test by using a dedicated sentinel keypair (distinct from manager) and asserting the created multicast publisher owner matches the IBRL user's owner

Diff Breakdown

Category	Files	Lines (+/-)	Net
Core logic	5	+364 / -28	+336
Scaffolding	3	+106 / -43	+63
Tests	1	+37 / -2	+35

Primarily new logic: nearest-device selection, device info fetching, and the owner bug fix account for the bulk of additions.

Key files (click to expand)

• crates/sentinel/src/nearest_device.rs — new module: Haversine distance, device capacity check, find_nearest_device_for_multicast
• crates/sentinel/src/dz_ledger_reader.rs — DzDeviceInfo struct and fetch_device_infos (batch fetches Device + Location accounts)
• controlplane/doublezero-admin/src/cli/sentinel.rs — CLI wiring for all new flags, NEAREST DEVICE column, dynamic device re-evaluation loop
• crates/sentinel/src/multicast_create.rs — CandidateFilters gets clients: Vec<String> and ips: Vec<Ipv4Addr>; find_candidates accepts device_infos
• crates/sentinel/src/dz_ledger_writer.rs — owner bug fix: explicit owner param used for PDA derivation, user_payer, and owner field (was using payer)
• crates/sentinel/src/multicast_find.rs — FindFilters.clients: Vec<String> replaces client: Option<String>
• e2e/sentinel_multicast_publisher_test.go — dedicated sentinel keypair setup; asserts u.Owner == dn.Manager.Pubkey

Testing Verification

• Unit tests in multicast_create.rs, multicast_find.rs, nearest_device.rs, and dz_ledger_writer.rs cover filter logic, capacity checks, Haversine distance, and instruction building with correct owner
• E2E test TestE2E_SentinelMulticastPublisherCreatesPublishers updated to use a separate sentinel keypair so the owner assertion would have caught the bug before this fix