feat(llamaswap): add llama-swaps (TLS) DSN scheme

llama-swap was http-only by DSN, pushing TLS-fronted instances onto the openai://
scheme (which loses the management/image methods). Add a "llama-swaps" scheme
that builds an https base URL, alongside "llama-swap" (http, local-first) —
mirroring redis/rediss. Both share one factory; llama-swaps is scheme-only (no
default built-in). The choice stays explicit because a DSN has no reliable
http-vs-https signal.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

builtin_llamaswap_test.go

@@ -51,6 +51,28 @@ func TestLlamaSwapScheme(t *testing.T) {
 	}
 }
 
+// TestLlamaSwapsScheme: the "llama-swaps" scheme builds an https base URL for a
+// TLS-fronted instance (vs "llama-swap" which is http local-first).
+func TestLlamaSwapsScheme(t *testing.T) {
+	r := newTestRegistry(t)
+	if err := r.LoadEnv(map[string]string{
+		"LLM_LST": "llama-swaps://tok@swap.example.com",
+	}); err != nil {
+		t.Fatalf("LoadEnv: %v", err)
+	}
+	p, ok := r.Provider("lst")
+	if !ok {
+		t.Fatal("provider \"lst\" not registered")
+	}
+	lp, ok := p.(*llamaswap.Provider)
+	if !ok {
+		t.Fatalf("provider is %T, want *llamaswap.Provider", p)
+	}
+	if want := "https://swap.example.com"; lp.BaseURL() != want {
+		t.Errorf("baseURL = %q, want %q", lp.BaseURL(), want)
+	}
+}
+
 // TestLlamaSwapBuiltinNoURL: the no-DSN built-in resolves but errors clearly on
 // use (mirrors foreman), rather than silently hitting a wrong host.
 func TestLlamaSwapBuiltinNoURL(t *testing.T) {