release: v0.2.0 — the dependency-major (alkcall 0.9.0 / alktunnels 0.3.0)

- Cargo.toml: alkcall 0.8.1 -> 0.9.0 (crates.io, the stub-sweep
  release) and alktunnels 0.2.1 -> 0.3.0 (its dependency-major ride);
  0.1.0 -> 0.2.0 (semver-incompatible dep bumps + public alkcall
  re-exports -> minor, matching the alktunnels 0.2.1 -> 0.3.0 ride)
- fuzz/shared/Cargo.toml: alkcall 0.9.0 (one alkcall version across
  the path graph)
- No code change: zero contact with the 0.9.0 breaking surface (no
  marked-pub registration, no control-handle subscription, no
  resource enumerator use, no generic op/register announcements;
  Establishment::default() is the only Establishment contact, in the
  session gate)
- CHANGELOG: 0.2.0 section + compare links
- README: the 0.2.0 note
- docs/architecture/overview.md: dep tree + feature table alkcall
  0.9.0 / alktunnels 0.3.0
- AGENTS.md: alkcall refs — v0.8.x/0.8.0 pin -> v0.9.x/0.9.0

Verification: cargo test (145 default / 171 all-features), fuzz/shared
corpus replay (3/3), clippy --all-targets -D warnings (native +
wasm32-unknown-unknown), fmt --check, wasm32 check, cargo doc, and
cargo publish --dry-run --allow-dirty all green

fuzz/shared/Cargo.toml

@@ -6,7 +6,7 @@ edition = "2021"
 
 [dependencies]
 alksocks = { path = "../.." }
-alkcall = "0.8.1"
+alkcall = "0.9.0"
 serde_json = "1"
 bytes = "1"
 tokio = { version = "1", features = ["rt", "io-util", "macros"], default-features = false }