feat: add support for order-filtering as stream combinators

[Fraser999]

[Claude Code]

Description

Adds stream combinators for filtering SignedOrder streams in signet-orders, plus a small supporting helper on SignedOrder itself.

• New OrderStreamExt trait with filter_orders, implemented for any Stream<Item = Result<SignedOrder, E>>. Err items pass through unchanged; only Ok items are tested against the predicate. The predicate is FnMut, so stateful filtering (e.g. dedup by order_hash) is supported.
• New stream::predicates module with ready-made predicate constructors: not_expired_at, has_output_chain, has_output_token, has_output_recipient, has_input_token, with_owner. Each returns impl Fn(&SignedOrder) -> bool and composes via boolean operators in a closure.
• New SignedOrder::is_expired_at(timestamp) on signet-types, factored out of validate so the deadline check has a single source of truth and can be reused by not_expired_at. Boundary semantics are unchanged (timestamp == deadline is not expired; U256 deadlines saturate to u64::MAX).
• Adds tokio (with macros, rt) as a [dev-dependencies] entry on signet-orders for the new #[tokio::test]s.
• Bumps the version to 0.16.3 of all crates.

Test plan

• cargo t -p signet-orders - new stream/predicate tests pass
• cargo t -p signet-types - existing validate behavior preserved
• cargo clippy -p signet-orders --all-features --all-targets
• cargo clippy -p signet-orders --no-default-features --all-targets
• cargo +nightly fmt -- --check
• RUSTDOCFLAGS="-D warnings" cargo doc -p signet-orders --no-deps - verifies the predicates module-level doctest compiles

[Fraser999]

• feat: add support for order-filtering as stream combinators #230 👈 (View in Graphite)
• main

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[prestwich]

one nit

[prestwich]

this could be ambiguous if tokens on host and RU share an address. should we do a (chain_id, address) tuple here maybe?

[prestwich]

slept on this. in extreme edge cases, an attacker can create this confusion. This should be caught downstream by additional filler quoting and pricing processes, but still better to do defense in depth here I think

[Fraser999]

Good point - addressed this in 6142c83.