feat: add DeepSeek, Moonshot, xAI, Groq, Ollama; drop v1; migrate TUI to v2

Five OpenAI-compatible providers join the library as first-class constructors
(llm.DeepSeek, llm.Moonshot, llm.XAI, llm.Groq, llm.Ollama). Their wire-level
implementation is shared via a new v2/openaicompat package which is the
extracted guts of the old v2/openai provider; each provider supplies its own
Rules value to declare per-model constraints (e.g., DeepSeek Reasoner rejects
tools and temperature, Moonshot/xAI accept images only on *-vision* models,
Groq rejects audio input). v2/openai itself becomes a thin wrapper that sets
RestrictTemperature for o-series and gpt-5 models.

A new provider registry (v2/registry.go) exposes llm.Providers() and drives
the TUI's provider picker so adding a provider in future is a single-file
change.

The TUI at cmd/llm was migrated from v1 to v2 and moved to v2/cmd/llm. With
nothing else depending on v1, the v1 code at the repo root (all .go files,
schema/, internal/, provider/, root go.mod/go.sum) is deleted.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

v2/xai/xai.go

@@ -0,0 +1,29 @@
+// Package xai implements the go-llm v2 provider interface for xAI (Grok,
+// https://x.ai/api). xAI speaks OpenAI Chat Completions, so this package is a
+// thin wrapper over openaicompat with its own defaults and per-model Rules.
+package xai
+
+import (
+	"strings"
+
+	"gitea.stevedudenhoeffer.com/steve/go-llm/v2/openaicompat"
+)
+
+// DefaultBaseURL is the public xAI API endpoint.
+const DefaultBaseURL = "https://api.x.ai/v1"
+
+// Provider is a type alias over openaicompat.Provider.
+type Provider = openaicompat.Provider
+
+// New creates a new xAI provider. An empty baseURL uses DefaultBaseURL.
+func New(apiKey, baseURL string) *Provider {
+	if baseURL == "" {
+		baseURL = DefaultBaseURL
+	}
+	return openaicompat.New(apiKey, baseURL, openaicompat.Rules{
+		// Grok models whose name contains "vision" accept images; others don't.
+		SupportsVision: func(m string) bool {
+			return strings.Contains(m, "vision")
+		},
+	})
+}

v2/xai/xai_test.go

@@ -0,0 +1,33 @@
+package xai_test
+
+import (
+	"context"
+	"errors"
+	"testing"
+
+	"gitea.stevedudenhoeffer.com/steve/go-llm/v2/openaicompat"
+	"gitea.stevedudenhoeffer.com/steve/go-llm/v2/provider"
+	"gitea.stevedudenhoeffer.com/steve/go-llm/v2/xai"
+)
+
+func TestNew_Basic(t *testing.T) {
+	if p := xai.New("key", ""); p == nil {
+		t.Fatal("New returned nil")
+	}
+}
+
+func TestRules_Grok2RejectsImages(t *testing.T) {
+	p := xai.New("key", "")
+	req := provider.Request{
+		Model: "grok-2",
+		Messages: []provider.Message{{
+			Role:   "user",
+			Images: []provider.Image{{URL: "a"}},
+		}},
+	}
+	_, err := p.Complete(context.Background(), req)
+	var fue *openaicompat.FeatureUnsupportedError
+	if !errors.As(err, &fue) || fue.Feature != "vision" {
+		t.Fatalf("want FeatureUnsupportedError(vision), got %v", err)
+	}
+}