refactor(core): make local constants crate-private

Decision K (spec §5): the local capacities and timings are defaults that
will become configuration, so they are `pub(crate)`. The wire constants
stay public.

- MAX_PEERS, SUMMARY_INTERVAL_MS, REASSEMBLY_TIMEOUT_MS, SEND_QUEUE_CAP,
  MIN_MTU, EVENT_QUEUE_CAP, DROP_TABLE_CAP, BCAST_SENT_CAP, ACK_BUFFER_CAP
  and PEER_IDLE_MS are now `pub(crate)`; a compile_fail doctest pins it.
- MIN_MTU's doc claimed it was the floor below which a fragment has no
  room. It is only the frag sweep's lower bound (BLE ATT's 23). The real
  floors are now stated on `Transport::mtu` and pinned by
  `consts::tests::mtu_floors`: 85 to carry every valid observation, 66 to
  fragment at all, 35 for an Ack, 26 for a summary.
- tines-bt caps live connections with its own MAX_PEERS (8).
- tines-sim's props mirror MAX_PEERS/SEND_QUEUE_CAP, checked against core
  through the hidden `conformance` module; the fuzz twin reads it there.
- node.rs: drain_events' rustdoc no longer links the now-private consts.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tines-sim/tests/props.rs

@@ -23,12 +23,28 @@
 //!   addressed candidate a turn. Pins §6's overflow-safety guarantee.
 
 use proptest::prelude::*;
-use tines_core::{
-    consts::{MAX_PEERS, SEND_QUEUE_CAP},
-    FrameBuf, Store,
-};
+use tines_core::{FrameBuf, Store};
 use tines_sim::{CappedStore, Contact, ContactTrace, Sim, WorldConfig};
 
+/// Mirrors tines-core's peer-table capacity, a crate-private local constant
+/// since 1.0 (decision K). `local_caps_match_core` checks the mirror.
+const MAX_PEERS: usize = 8;
+
+/// Mirrors tines-core's send-queue / bounce-table capacity, a crate-private
+/// local constant since 1.0 (decision K). `local_caps_match_core` checks the
+/// mirror.
+const SEND_QUEUE_CAP: usize = 256;
+
+/// The mirrored local caps still equal core's. Runs with the `conformance`
+/// feature (as `scripts/ci.sh` does), which exposes core's values through its
+/// hidden `conformance` module.
+#[cfg(feature = "conformance")]
+#[test]
+fn local_caps_match_core() {
+    assert_eq!(MAX_PEERS, tines_core::conformance::MAX_PEERS);
+    assert_eq!(SEND_QUEUE_CAP, tines_core::conformance::SEND_QUEUE_CAP);
+}
+
 /// A fixed set of short observation topics the tests reuse so the generated
 /// observations round-trip cleanly through the core (`MAX_TOPIC` is 64 bytes).
 const TOPICS: [&[u8]; 8] = [
@@ -166,7 +182,7 @@ fn addressed_scenario() -> impl Strategy<Value = (usize, usize, ContactTrace)> {
 /// graph plus a flood of distinct addressed observations past [`SEND_QUEUE_CAP`].
 #[derive(Debug)]
 struct BounceScenario {
-    /// Node count (fixed at [`consts::MAX_PEERS`]).
+    /// Node count (fixed at [`MAX_PEERS`]).
     nodes: usize,
     /// Fully-connected trace: every pair in contact during one long window.
     trace: ContactTrace,