chore: prepublish review — bump to 0.3.0, changelog, doc alignment

0.2.0 is already on crates.io (2026-08-31, c16b069); the review
004/005 remediation work is unreleased on top of it and lands as
0.3.0.

- Bump version 0.2.0 -> 0.3.0. Two OperationRegistry methods changed
  borrowed returns to owned (registration, list_operations) —
  source-breaking for annotated call sites, minor bump per 0.x
  semver rules. cargo semver-checks passes (196 checks) against the
  published baseline; the return-type changes were caught by manual
  diff review.
- CHANGELOG 0.3.0: connect-side serving (from_connection_with_serving
  + ServingConfig), OperationRegistry::fork + builder from_registry,
  registry::op_register (bootstrap op, collision policy,
  ALREADY_EXISTS), install_bootstrap_discovery, spec_to_json_pub +
  resource_id_path round-trip, overlay accessors, concurrent serving
  loops, &self registration.
- README: serving-as-consumer section, consumer role table update,
  drop the stale `mut` on the registry example.
- AGENTS.md: ADR range 001..047 -> 001..048.
- Fix rustdoc private-intra-doc-link warning on StartedDispatch.

Verification: 589 default / 606 all-features tests, clippy
(all-targets, all-features, wasm32) clean, fmt clean, doc clean,
publish dry-run OK.

AGENTS.md

@@ -215,13 +215,14 @@ cargo semver-checks check-release             # before a release
 ## Architecture Context
 
 - `docs/architecture/` — the authoritative spec. Read it before
-  non-trivial changes. ADRs are numbered 001..047; OQs (open questions)
+  non-trivial changes. ADRs are numbered 001..048; OQs (open questions)
   track resolved/deferred decisions.
 - This crate unifies `alknet-call` and `alknet-channels` from the
   alknet mono-repo (`/workspace/@alkdev/alknet`). The source
   architecture docs were ported from
   `/workspace/@alkdev/alknet/docs/architecture/` and renumbered as
-  alkcall ADRs (001..047). The ALPN strings (`alk/call`,
+  alkcall ADRs (001..048; ADR-048 was authored in this crate). The ALPN
+  strings (`alk/call`,
   `alk/channels`) are wire-stable going forward (renamed from
   `alknet/` to `alk/` in v0.1.1, before the first published consumer).
 - Key ADRs that inform this crate's design: