server: SdStateHandle trait + drop Arc<SdStateManager> requirement

[JustinKovacich]

Adds SdStateHandle + WrappableSdStateHandle traits in src/server/sd_state.rs and threads them through Server as a new Hsd type parameter (default Arc<SdStateManager>). Mirrors the pattern established by 19f's SocketHandle /
WrappableSocketHandle. Same shape, same Send/Sync defaults (neither bound at trait level — caller adds at use sites).

Two impls ship:

• Arc<SdStateManager>: SdStateHandle + WrappableSdStateHandle (the existing default; preserves std-side behavior).
• &'static SdStateManager: SdStateHandle (no-alloc; user declares static SD_STATE: SdStateManager = SdStateManager::new(); and supplies &SD_STATE via a future Server::new_with_handles constructor).

SdStateManager itself becomes pub and SdStateManager::new() becomes pub const fn so the static-storage pattern compiles. The internal methods (next_session_id_with_reboot_flag, reboot_flag, send_offer_service) stay pub(super) — consumers shouldn't call them directly; they go through Server.

Server's existing new_with_deps / new_passive_with_deps constructors require Hsd: WrappableSdStateHandle because they build the manager internally via SdStateManager::new() then Hsd::wrap(...). The future Server::new_with_handles will take Hsd: SdStateHandle directly (no wrap step), enabling the no-alloc path with &'static SdStateManager.

announcement_loop's method-level where clause picks up the new Hsd: Send + Sync bound, mirroring the existing H: Send + Sync and F: Send + Sync bounds. The _local variant has no such requirement and works for any Hsd: SdStateHandle.

Type-signature width: Server now reads Server<R, S, F, Tm, H = Arc<F::Socket>, Hsd = Arc<SdStateManager>>. Both defaults preserve every existing call site — Server<R, S, F, Tm> and Server<R, S, F, Tm, Arc<SomeSocket>> both still resolve correctly. No churn in tests/ or examples/.

Clears 20-pre alloc audit's category-E.2 finding. Combined with the 4f9d36e recv-buffer split, two of the four "no-alloc Server" remediation items are done.

What this leaves:

• E.1: Arc<EventPublisher<R, S, H>> field on Server. Same shape via an EventPublisherHandle trait — next branch.
• D: Server::new_with_handles constructor that takes pre-built H + Hsd (and the future Hep for E.1) directly, skipping the wrap step. Lands after E.1 so the constructor's parameter list is final.

Gates green:

• cargo fmt --check
• cargo clippy --tests (2 pre-existing warnings, unrelated)
• cargo build --workspace --all-targets
• cargo build --no-default-features --features client,server,bare_metal
• cargo build -p simple-someip-embassy-net --target thumbv7em-none-eabihf
• cargo test --features client-tokio,server-tokio --test client_server -- --test-threads=1 (11/11)
• cargo test --features client,server,bare_metal --test bare_metal_e2e (2/2)
• cargo test -p simple-someip-embassy-net --test loopback (3/3)

[Copilot]

Pull request overview

This PR introduces a handle abstraction for server-side SD session state (SdStateHandle / WrappableSdStateHandle) and threads it through Server as a new type parameter (Hsd, defaulting to Arc<SdStateManager>), enabling future no-alloc usage patterns without requiring Arc<SdStateManager>.

Changes:

• Add SdStateHandle and WrappableSdStateHandle traits plus implementations for Arc<SdStateManager> and &'static SdStateManager.
• Make SdStateManager public and SdStateManager::new() a pub const fn to support static-storage construction.
• Update Server to store SD state behind Hsd and use SdStateHandle::sd_state() at call sites; add method-level Send + Sync bounds for announcement_loop.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/server/sd_state.rs	Makes SdStateManager public/const-constructible and adds SD-state handle traits + impls.
src/server/mod.rs	Adds Hsd type parameter to Server and migrates SD-state usage to the new handle abstraction.

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[Copilot]

SdStateManager is now public, but its rustdoc still claims it "exposes" the reboot state via Self::reboot_flag (and links to it). reboot_flag is #[cfg(test)] pub(super), so it won’t exist in normal builds and the public docs are now inaccurate / can produce a broken intra-doc link. Suggest updating this doc to describe the public surface (e.g., refer to next_session_id_with_reboot_flag semantics or state that reboot-flag tracking is internal to Server) and remove the Self::reboot_flag link rather than making that method public.