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>

CLAUDE.md

@@ -1,88 +1,31 @@
 # CLAUDE.md for go-llm
 
-## Build and Test Commands
-- Build project: `go build ./...`
-- Run all tests: `go test ./...`
-- Run specific test: `go test -v -run <TestName> ./...`
-- Tidy dependencies: `go mod tidy`
+All Go code now lives under `v2/`. The module path is
+`gitea.stevedudenhoeffer.com/steve/go-llm/v2`. There is no module at the
+repository root anymore; the v1 code at the root was deleted after all
+consumers migrated to v2.
 
-## Code Style Guidelines
-- **Indentation**: Use standard Go tabs for indentation.
-- **Naming**: 
-  - Use `camelCase` for internal/private variables and functions.
-  - Use `PascalCase` for exported types, functions, and struct fields.
-  - Interface names should be concise (e.g., `LLM`, `ChatCompletion`).
-- **Error Handling**:
-  - Always check and handle errors immediately.
-  - Wrap errors with context using `fmt.Errorf("%w: ...", err)`.
-  - Use the project's internal `Error` struct in `error.go` when differentiating between error types is needed.
-- **Project Structure**:
-  - `llm.go`: Contains core interfaces (`LLM`, `ChatCompletion`) and shared types (`Message`, `Role`, `Image`).
-  - Provider implementations are in `openai.go`, `anthropic.go`, and `google.go`.
-  - Schema definitions for tool calling are in the `schema/` directory.
-  - `mcp.go`: MCP (Model Context Protocol) client integration for connecting to MCP servers.
-- **Imports**: Organize imports into groups: standard library, then third-party libraries.
-- **Documentation**: Use standard Go doc comments for exported symbols.
-- **README.md**: The README.md file should always be kept up to date with any significant changes to the project.
+See `v2/CLAUDE.md` for build/test commands and per-package guidance.
 
-## CLI Tool
-- Build CLI: `go build ./cmd/llm`
-- Run CLI: `./llm` (or `llm.exe` on Windows)
-- Run without building: `go run ./cmd/llm`
+## CLI
 
-### CLI Features
-- Interactive TUI for testing all go-llm features
-- Support for OpenAI, Anthropic, and Google providers
-- Image input (file path, URL, or base64)
-- Tool/function calling with demo tools
-- Temperature control and settings
+The interactive TUI lives at `v2/cmd/llm`:
 
-### Key Bindings
-- `Enter` - Send message
-- `Ctrl+I` - Add image
-- `Ctrl+T` - Toggle tools panel
-- `Ctrl+P` - Change provider
-- `Ctrl+M` - Change model
-- `Ctrl+S` - Settings
-- `Ctrl+N` - New conversation
-- `Esc` - Exit/Cancel
-
-## MCP (Model Context Protocol) Support
-
-The library supports connecting to MCP servers to use their tools. MCP servers can be connected via:
-- **stdio**: Run a command as a subprocess
-- **sse**: Connect to an SSE endpoint
-- **http**: Connect to a streamable HTTP endpoint
-
-### Usage Example
-```go
-ctx := context.Background()
-
-// Create and connect to an MCP server
-server := &llm.MCPServer{
-    Name:    "my-server",
-    Command: "my-mcp-server",
-    Args:    []string{"--some-flag"},
-}
-if err := server.Connect(ctx); err != nil {
-    log.Fatal(err)
-}
-defer server.Close()
-
-// Add the server to a toolbox
-toolbox := llm.NewToolBox().WithMCPServer(server)
-
-// Use the toolbox in requests - MCP tools are automatically available
-req := llm.Request{
-    Messages: []llm.Message{{Role: llm.RoleUser, Text: "Use the MCP tool"}},
-    Toolbox:  toolbox,
-}
+```
+cd v2 && go run ./cmd/llm
 ```
 
-### MCPServer Options
-- `Name`: Friendly name for logging
-- `Command`: Command to run (for stdio transport)
-- `Args`: Command arguments
-- `Env`: Additional environment variables
-- `URL`: Endpoint URL (for sse/http transport)
-- `Transport`: "stdio" (default), "sse", or "http"
+It iterates `llm.Providers()` so every registered provider (OpenAI, Anthropic,
+Google, DeepSeek, Moonshot, xAI, Groq, Ollama) appears in the picker
+automatically. Status is derived from each provider's env var; Ollama shows as
+"(local)" because it needs no key.
+
+### Key bindings
+- `Enter` — Send message
+- `Ctrl+I` — Add image
+- `Ctrl+T` — Toggle tools panel
+- `Ctrl+P` — Change provider
+- `Ctrl+M` — Change model
+- `Ctrl+S` — Settings
+- `Ctrl+N` — New conversation
+- `Esc` — Exit/Cancel