feat: initial llm-chat v0.1.0 (llm.chat@0.1.0)

Generic Ollama-compatible LLM chat adapter. The lower-level
counterpart to orchestrator-llm: orchestrator-llm wraps the LLM
in a planning prompt that emits a structured F∆I Plan; this
module is the plain-prompt adapter that flows compose for
summarisation, translation, free-form Q&A, etc.

Capability surface:

  Inputs:
    prompt        : text
    endpoint      : text   (Ollama /api/chat URL)
    model         : text
    api_key       : text   (optional bearer token)
    system_prompt : text   (optional)

  Outputs:
    response       : text   (assistant reply)
    model_endpoint : text   (audit correlation)
    model_name     : text   (audit correlation)
    model_digest   : text   (Ollama /api/show probe; empty
                              for non-Ollama or transient failures)

  Permissions: net to localhost / 127.0.0.1 / api.openai.com /
               api.anthropic.com.

The audit-field trio (endpoint + name + digest) closes the same
forensic gap that orchestrator-llm v0.3.1 closed for plan
generation: any historical chat invocation can be traced to the
exact model that produced it.

Implementation reuses the same defensive Ollama client pattern
from orchestrator-llm — derive_show_url + extract_show_digest
+ best-effort probe_model_digest. Duplication accepted at the
two-module mark; a shared crate refactor lands once a third
module needs the same plumbing.

12 host-side tests cover prompt building, Ollama-shaped
response parsing, URL transform, digest extraction (top-level
+ nested), end-to-end success, end-to-end probe-failure
swallow, end-to-end skip-for-non-Ollama, and the missing-input
guards.

Wasm artifact: 294 KB. Verified to build with v1.0 fai:platform
imports baked in.

Bootstrapped via 'fai new module llm.chat' (workspace v0.10.13)
which now produces an SDK-based template directly.

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

Cargo.toml

@@ -0,0 +1,49 @@
+# Standalone Cargo.toml — targets wasm32-wasip2.
+#
+# Build with:
+#   cargo build --release --target wasm32-wasip2
+
+[package]
+name = "llm_chat"
+version = "0.1.0"
+edition = "2024"
+license = "Apache-2.0"
+publish = false
+description = "F∆I module providing llm.chat"
+
+[lib]
+# cdylib for the wasm artifact, rlib so integration tests can
+# link against the module's `invoke` function on the host.
+crate-type = ["cdylib", "rlib"]
+
+[dependencies]
+fai-module-sdk = { git = "https://git.flemming.ws/fai/module-sdk.git", branch = "main" }
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
+thiserror = "2"
+
+# WASI-0.2 HTTP client. Only compiled into the wasm32-wasip2 build.
+[target.'cfg(target_arch = "wasm32")'.dependencies]
+waki = "0.5"
+
+[dev-dependencies]
+serde_json = "1"
+
+[profile.release]
+opt-level = "s"
+lto = true
+codegen-units = 1
+strip = "symbols"
+
+[lints.rust]
+unsafe_op_in_unsafe_fn = "warn"
+
+[lints.clippy]
+unwrap_used = "deny"
+expect_used = "deny"
+panic = "deny"
+print_stdout = "deny"
+print_stderr = "deny"
+
+[workspace]
+# Empty so this package is NOT picked up by a parent.