proto/bloom: relocate bloom filter into sans-IO layout

Migrate the v1 bloom filter subsystem into src/proto/bloom/, matching the
discovery/routing/fmp/mmp/stp reference layout and completing the proto/
relocation series for the data/wire subsystems.

- wire.rs: the FilterAnnounce (0x20) codec, moved from protocol/filter.rs
- core.rs: the pure BloomFilter algorithm (hash/insert/contains/merge/
  as_bytes/from_bytes/estimated_count), moved from bloom/filter.rs
- state.rs: BloomState (per-peer inbound store, compute_outgoing_filter,
  the injected-clock send debounce), moved from bloom/state.rs
- limits.rs: the v1 sizing constants
- mod.rs: module wiring + the BloomError enum
- tests/: the unit suite split by target (core/state/wire), no inline tests

no_std+alloc hygiene: core::fmt over std::fmt, the tracing dependency
dropped from the pure filter, and std collections replaced with
BTreeMap/BTreeSet (NodeAddr: Ord) for deterministic iteration. The pure
filter combination stays a BloomState method; the two irreducible shell
gathers (peer_inbound_filters, build_filter_announce) remain in the async
shell. Wire bytes and observable behavior are unchanged; full local CI
green (36/36) including the bloom-storm chaos gate.

src/node/mod.rs

@@ -40,10 +40,10 @@ use self::wire::{
     ESTABLISHED_HEADER_SIZE, FLAG_CE, FLAG_KEY_EPOCH, FLAG_SP, build_encrypted,
     build_established_header, prepend_inner_header,
 };
-use crate::bloom::{BloomFilter, BloomState};
 use crate::cache::CoordCache;
 use crate::node::session::SessionEntry;
 use crate::peer::{ActivePeer, PeerConnection};
+use crate::proto::bloom::{BloomFilter, BloomState};
 use crate::proto::discovery::{Discovery, DiscoveryBackoff, DiscoveryForwardRateLimiter};
 use crate::proto::fmp::Fmp;
 use crate::proto::mmp::Mmp;