Clean up rebranding drift in docs, agent configs, and source comments

Fix stale references left over from the alknet-typedef → alktype migration:
- .opencode/agents/: replace @alkdev/alknet constraints (tokio, crypto, feature
  flags, anyhow/thiserror) with alktype-accurate ones (sync, AlkTypeError,
  WASM-clean); fix @alkimiadev → @alkdev org name; remove nonexistent AGENTS.md
  ref; replace alknet-http/alknet-agent spec examples
- docs/sdd_process.md: fix wrong package name (@alkdev/storage → @alkdev/alktype)
- docs/architecture/: rewrite dangling /workspace/ and docs/research/ paths as
  @alkdev/alknet: cross-repo references with explanatory notes; fix
  @alkimiadev → @alkdev; fix 'not yet used by any alknet crate' stale context
- src/ + tests/: correct '17 AlkType kinds' → '19' in doc comments (enum has 19
  variants; pre-existing count error); fix dangling /workspace/ path in
  poc_roundtrip.rs

src/lib.rs

@@ -17,7 +17,7 @@
 //! - **TUnion dispatch** ([`tunion`]): Byte-offset and field-name
 //!   discriminator dispatch.
 //! - **Validation** ([`validation`]): Custom keyword validators for all
-//!   17 `AlkType:*` kinds, delegated to the `jsonschema` crate.
+//!   19 `AlkType:*` kinds, delegated to the `jsonschema` crate.
 //! - **Engine** ([`engine`]): `AlkTypeEngine` — the compiled form of a
 //!   schema, combining layout and validation.