docs: document llm.toml and llama-swap metadata discovery

README, CLAUDE.md and .env.example now point at llm.toml for LLM settings
(OPENROUTER_API_KEY stays in env) and describe the legacy env override
window, the discovered picker and the startup cross-check. ADR-0003 records
the move and amends ADR-0002's deployment-config home; CONTEXT.md's
Deployment config / Hard default entries follow. Source comments and the
"set LLAMA_SWAP_URL" error strings name the llm.toml keys.

Also fixes README's AGENTIC_MAX_ITERATIONS default (10 -> 12, what the
code uses).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/ai/tts.rs

@@ -391,7 +391,7 @@ pub async fn tts_speech_handler(
     let Some(client) = app_state.llamacpp.as_ref() else {
         span.set_status(Status::error("tts backend not configured"));
         return HttpResponse::ServiceUnavailable()
-            .json(json!({ "error": "TTS backend not configured (set LLAMA_SWAP_URL)" }));
+            .json(json!({ "error": "TTS backend not configured (set llamacpp.url in llm.toml)" }));
     };
 
     let format = req
@@ -521,7 +521,7 @@ pub async fn create_speech_job_handler(
     if app_state.llamacpp.is_none() {
         span.set_status(Status::error("tts backend not configured"));
         return HttpResponse::ServiceUnavailable()
-            .json(json!({ "error": "TTS backend not configured (set LLAMA_SWAP_URL)" }));
+            .json(json!({ "error": "TTS backend not configured (set llamacpp.url in llm.toml)" }));
     }
 
     let format = req
@@ -958,7 +958,7 @@ pub struct CreateVoiceFromLibraryRequest {
     /// lets the client pick the clean-speech section of a long recording.
     #[serde(default)]
     pub start_seconds: Option<f64>,
-    /// Reference window length; clamped to LLAMA_SWAP_TTS_REF_SECONDS.
+    /// Reference window length; clamped to `tts.ref_seconds`.
     #[serde(default)]
     pub duration_seconds: Option<f64>,
 }
@@ -966,7 +966,7 @@ pub struct CreateVoiceFromLibraryRequest {
 /// POST /tts/voices/from-library — register a cloned voice from a file already
 /// in a library. Audio and video alike are ffmpeg-normalized to a mono 24 kHz
 /// WAV reference clip (window selected by start/duration_seconds, length
-/// capped by LLAMA_SWAP_TTS_REF_SECONDS).
+/// capped by `tts.ref_seconds`).
 #[post("/tts/voices/from-library")]
 #[tracing::instrument(name = "http.tts.voices.from_library", skip_all)]
 pub async fn create_voice_from_library_handler(
@@ -1153,7 +1153,7 @@ mod tests {
 
     #[test]
     fn resolve_ref_window_defaults_to_start_of_clip_at_cap_length() {
-        // Reads the live cap rather than mutating LLAMA_SWAP_TTS_REF_SECONDS:
+        // Reads the live cap rather than mutating `tts.ref_seconds`:
         // env mutation flakes under the parallel suite (see env_dispatch).
         let cap = f64::from(tts_ref_seconds());
         assert_eq!(resolve_ref_window(None, None), Ok((0.0, cap)));