Add go-llm v2: redesigned API for simpler LLM abstraction

v2 is a new Go module (v2/) with a dramatically simpler API:
- Unified Message type (no more Input marker interface)
- Define[T] for ergonomic tool creation with standard context.Context
- Chat session with automatic tool-call loop (agent loop)
- Streaming via pull-based StreamReader
- MCP one-call connect (MCPStdioServer, MCPHTTPServer, MCPSSEServer)
- Middleware support (logging, retry, timeout, usage tracking)
- Decoupled JSON Schema (map[string]any, no provider coupling)
- Sample tools: WebSearch, Browser, Exec, ReadFile, WriteFile, HTTP
- Providers: OpenAI, Anthropic, Google (all with streaming)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

v2/tools/browser.go

@@ -0,0 +1,59 @@
+package tools
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+
+	llm "gitea.stevedudenhoeffer.com/steve/go-llm/v2"
+)
+
+// BrowserParams defines parameters for the browser tool.
+type BrowserParams struct {
+	URL string `json:"url" description:"The URL to fetch and extract text from"`
+}
+
+// Browser creates a simple web content fetcher tool.
+// It fetches a URL and returns the text content.
+//
+// For a full headless browser, consider using an MCP server like Playwright MCP.
+//
+// Example:
+//
+//	tools := llm.NewToolBox(tools.Browser())
+func Browser() llm.Tool {
+	return llm.Define[BrowserParams]("browser", "Fetch a web page and return its text content",
+		func(ctx context.Context, p BrowserParams) (string, error) {
+			req, err := http.NewRequestWithContext(ctx, http.MethodGet, p.URL, nil)
+			if err != nil {
+				return "", fmt.Errorf("creating request: %w", err)
+			}
+			req.Header.Set("User-Agent", "go-llm/2.0 (Web Fetcher)")
+
+			resp, err := http.DefaultClient.Do(req)
+			if err != nil {
+				return "", fmt.Errorf("fetching URL: %w", err)
+			}
+			defer resp.Body.Close()
+
+			// Limit to 1MB
+			limited := io.LimitReader(resp.Body, 1<<20)
+			body, err := io.ReadAll(limited)
+			if err != nil {
+				return "", fmt.Errorf("reading body: %w", err)
+			}
+
+			result := map[string]any{
+				"url":          p.URL,
+				"status":       resp.StatusCode,
+				"content_type": resp.Header.Get("Content-Type"),
+				"body":         string(body),
+			}
+
+			out, _ := json.MarshalIndent(result, "", "  ")
+			return string(out), nil
+		},
+	)
+}