feat(ai): discover the llama-swap picker and vision from model metadata

/insights/models now lists llama-swap's models live from /v1/models
instead of LLAMA_SWAP_ALLOWED_MODELS: every kind=chat model, with
setParamsByID aliases (:sub / :fast) hidden, filtered by
[llamacpp.picker] exclude and the optional include allowlist. Ids the
include list names but llama-swap no longer serves drop out instead of
showing as dead picker entries.

has_vision and context_window come from each model's config.yaml metadata
(read from meta.llamaswap, where the deployed llama-swap merges it, or from
meta as upstream documents). A model without metadata is text-only chat.
A live served window still wins over the configured ctx.

Agentic insights on llama-swap now ask the chat model's capabilities:
text-only models (e.g. qwen3.8-27b-code, --no-mmproj) get the local vision
model's description inlined, like hybrid, instead of an image they can't
read. If llama-swap can't be asked, images are sent as before.

Drops AppState.llamacpp_allowed_models.

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

src/ai/insight_generator.rs

@@ -4447,7 +4447,7 @@ Return ONLY the summary, nothing else."#,
         } else if local_via_llamacpp {
             // Local via llama-swap.
             let arc = self.llamacpp.as_ref().ok_or_else(|| {
-                anyhow::anyhow!("LLM_BACKEND=llamacpp but LLAMA_SWAP_URL not configured")
+                anyhow::anyhow!("backend = \"llamacpp\" but llamacpp.url not configured")
             })?;
             let mut c: LlamaCppClient = (**arc).clone();
             if let Some(ref m) = overrides.model {
@@ -4515,11 +4515,22 @@ Return ONLY the summary, nothing else."#,
             // Hybrid: chat model never sees images — describe-then-inject.
             false
         } else if local_via_llamacpp {
-            // llama-swap models receive images directly via OpenAI content
-            // parts. Capability probing isn't available (no `/api/show`),
-            // so assume vision support; a misconfigured model surfaces as
-            // a chat-call error.
-            true
+            // Vision models get images directly via OpenAI content parts;
+            // text-only ones (metadata `vision: false`) get the local vision
+            // model's description inlined instead, like hybrid. If llama-swap
+            // can't be asked, assume vision — the chat call will say why.
+            let lc = self
+                .llamacpp
+                .as_deref()
+                .expect("checked by local_via_llamacpp");
+            let model = overrides.model.as_deref().unwrap_or(&lc.primary_model);
+            match lc.model_capabilities(model).await {
+                Ok(caps) => caps.has_vision,
+                Err(e) => {
+                    log::warn!("vision capability unknown for '{model}', sending images: {e:#}");
+                    true
+                }
+            }
         } else {
             // Pure Ollama: probe model capabilities.
             let ollama_for_caps = if let Some(ref model) = overrides.model {