release: v0.2.0 — the graduation (direct op + bind-first/forwarded metadata flow)

- README sync: the direct op (ADR-007), the bind-first establisher +
  the forwarded op (ADR-008), TunnelListener + the reply-field
  projection, the 0.2 summary section, the local bind-first helpers
- CHANGELOG: Unreleased cut to 0.2.0 (the graduation + the alkcall
  0.8.0 bump; compare links updated)
- Cargo.toml: 0.1.0 -> 0.2.0

Verification: cargo test (135 pass default / 162 with local), clippy
(all targets, -D warnings, both feature sets), fmt, doc, the
wasm32-unknown-unknown check + clippy, and cargo publish --dry-run
--allow-dirty all green

Cargo.lock

@@ -48,7 +48,7 @@ dependencies = [
 
 [[package]]
 name = "alktunnels"
-version = "0.1.0"
+version = "0.2.0"
 dependencies = [
  "alkcall",
  "bytes",