docs(architecture): resolve review #002 Tiers 1-3 — mechanical and consistency fixes

Governance (Tier 2):
- Advance ADR-022 and ADR-023 from Proposed to Accepted (specs already
  depend on their types as source of truth)
- Amend ADR-015: mark Decision 3 and Assumption 6 as superseded by ADR-022;
  update handler_identity type to CompositionAuthority
- Amend ADR-002: note handle() signature revised by ADR-007 (BiStream → Connection)
- Amend ADR-004: note 'enrich/replace' AuthContext language superseded by
  ADR-011's immutability model; update to describe set_identity on Connection
- Update main README ADR table to show ADR-022/023 as Accepted

Spec-ADR consistency (Tier 3):
- Add abort_policy: AbortPolicy field to OperationContext struct (ADR-016
  Decision 6 mandated this but the spec omitted it)
- Define AbortPolicy enum (AbortDependents | ContinueRunning) with Default impl
- Add abort_policy to build_root_context and LocalOperationEnv::invoke()
- Define the OperationEnv trait explicitly with invoke() and
  invoke_with_policy() methods (was referenced as 'must remain a trait'
  but never defined)
- Specify From<StreamError> for HandlerError impl with exact variant mapping
- Add Connection::from_quinn() / from_iroh() constructors (was referenced
  as Connection::new() but never defined)
- Remove undefined CertAuthorityEntry placeholder from AuthPolicy v1 (will
  be added additively when alknet-ssh lands)
- Fix config.md key-differences table: rate limits are in DynamicConfig,
  not StaticConfig

Mechanical fixes (Tier 1):
- overview.md: 'closes the QUIC stream' → 'closes the connection' (stale
  from pre-ADR-007 model)
- overview.md: OQ-04 entry updated from stale 'defer to implementation'
  to 'resolved: static at startup'
- mnemonic-derivation.md: remove duplicate helper functions block (incomplete
  first copy, complete second copy)
- ADR-003: add iroh (feature-gated) to alknet-core dependency list, added
  by ADR-010
- ADR-021: fix ambiguous 'W1 drift issue from the vault review' cross-reference
- ADR-022: rephrase FromCall 'leaf locally' to 'leaf in the local registry'
- ADR-017: add error_schemas to from_call mirror list and services/schema
  step (inconsistency with ADR-023)
- ADR-016: fix self-referential citation ('ADR-016 Assumption 5' → 'Assumption 5')
- Add ScopedOperationEnv::empty(), allows(), new() and
  CompositionAuthority::none(), new() impl blocks (referenced but undefined)
- Add call.completed clarification for non-subscription calls
- Add services/schema leading-slash normalization note
- Crate README ADR tables: add missing ADR-013 (call), ADR-015 (core),
  ADR-006 + ADR-010 (vault)
- Vault README: add consolidated 'Known Source Drift' table tracking all
  four drift items (OsRng, unwrap, CURRENT_KEY_VERSION, spawn bug) in one
  place, including the two previously missing from README

docs/architecture/decisions/002-protocol-handler-trait.md

@@ -16,19 +16,27 @@ iroh's `ProtocolHandler` trait demonstrates this: it takes a bidirectional QUIC
 
 A single `ProtocolHandler` trait replaces both `StreamInterface` and `MessageInterface`:
 
+> **Note**: The signature below was revised by ADR-007. The `handle()` method
+> now receives a `Connection` (not a `BiStream`) — see ADR-007 for the
+> current authoritative signature. The original signature is retained here
+> for historical context.
+
 ```rust
 #[async_trait]
 pub trait ProtocolHandler: Send + Sync + 'static {
     /// The ALPN string this handler claims (e.g. b"alknet/ssh")
     fn alpn(&self) -> &'static [u8];
 
-    /// Handle an incoming bidirectional QUIC stream
-    async fn handle(&self, stream: BiStream, auth: &AuthContext) -> Result<(), HandlerError>;
+    /// Handle an incoming connection (revised by ADR-007 to receive
+    /// `Connection` instead of `BiStream`)
+    async fn handle(&self, connection: Connection, auth: &AuthContext) -> Result<(), HandlerError>;
 }
 ```
 
 - `alpn()` returns a static byte string — the handler's ALPN identifier
-- `handle()` receives a `BiStream` (a joined `(SendStream, RecvStream)` implementing `AsyncRead + AsyncWrite`) and an `AuthContext` carrying the authenticated identity, and returns `HandlerError` on failure
+- `handle()` receives a `Connection` (revised by ADR-007 from the original
+  `BiStream`) and an `AuthContext` carrying the authenticated identity, and
+  returns `HandlerError` on failure
 - Every handler manages its own wire format — no shared framing, no StreamInterface/MessageInterface split
 - The `ListenerConfig` enum is eliminated — ALPN advertisement configuration replaces it