feat: migrate orchestrator-llm to fai-module-sdk (v0.3.0)

The module now uses the #[fai_module] macro from
fai-module-sdk v0.1.2. The behavior is unchanged from v0.2.1 —
deterministic stub when llm_endpoint is empty, real Ollama-shaped
HTTP otherwise. The migration drops:

  - The hand-written wit_bindgen::generate! invocation
  - The exports::fai::platform::invoke::Guest impl boilerplate
  - The unsafe_op_in_unsafe_fn allow workaround
  - The manual export!() macro call
  - The text_input helper that matched Payload variants by hand
  - The wit/ directory mirror of the platform's frozen WIT

In their place, the module body is one annotated function:

  #[fai_module]
  pub fn invoke(_ctx: Context, inputs: Inputs)
      -> Result<Outputs, ModuleError>
  { ... }

Compared with v0.2.1, lib.rs lost ~70 lines of WASM plumbing.
The SDK macro emits the WIT glue only on target_arch = wasm32
so the host build now compiles cleanly without a manual gate.
That removed two #[cfg(target_arch = wasm32)] blocks in the
process.

The Cargo.toml dep on wit-bindgen is replaced by a single git
dep on fai-module-sdk (branch=main, transitively pinning v0.1.2).
The macros crate comes through transitively. waki stays as a
target-gated dep — the SDK does not (yet) abstract HTTP.

Output payload extends the v0.2.1 schema additively: alongside
the existing 'plan' (JSON Plan), the module now emits
'model_endpoint' and 'model_name' so consumers (and audit logs)
can identify which LLM produced which plan. Existing flows that
only consume 'plan' are unaffected.

Wasm artifact verified to build with v1.0 imports. Platform-side
integration tests in fai/platform :: orchestrator_llm_path.rs
and orchestrator_module.rs pass against the migrated wasm with
no platform-side changes. Total platform suite: 151 green.

The wit/ directory is removed because the SDK ships the WIT
inline via include_str! at proc-macro compile time. Module repos
no longer maintain their own mirror copy.

Bumps the module to 0.3.0 (minor — output schema additively
extended).

Signed-off-by: flemming-it <sf@flemming.it>

Cargo.toml

@@ -5,7 +5,7 @@
 
 [package]
 name = "orchestrator_llm"
-version = "0.2.1"
+version = "0.3.0"
 edition = "2024"
 authors = ["Dr. Stefan Flemming <platform@flemming.ai>"]
 license = "Apache-2.0"
@@ -17,7 +17,7 @@ repository = "https://git.flemming.ws/fai-modules/orchestrator-llm"
 crate-type = ["cdylib", "rlib"]
 
 [dependencies]
-wit-bindgen = "0.36"
+fai-module-sdk = { git = "https://git.flemming.ws/fai/module-sdk.git", branch = "main" }
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 thiserror = "2"