feat: add Venice AI provider integration

Venice AI is a privacy-focused AI inference provider with support for
uncensored models and access to major proprietary models via their
anonymized proxy.

This integration adds:

- Complete model catalog with 25 models:
  - 15 private models (Llama, Qwen, DeepSeek, Venice Uncensored, etc.)
  - 10 anonymized models (Claude, GPT-5.2, Gemini, Grok, Kimi, MiniMax)
- Auto-discovery from Venice API with fallback to static catalog
- VENICE_API_KEY environment variable support
- Interactive onboarding via 'venice-api-key' auth choice
- Model selection prompt showing all available Venice models
- Provider auto-registration when API key is detected
- Comprehensive documentation covering:
  - Privacy modes (private vs anonymized)
  - All 25 models with context windows and features
  - Streaming, function calling, and vision support
  - Model selection recommendations

Privacy modes:
- Private: Fully private, no logging (open-source models)
- Anonymized: Proxied through Venice (proprietary models)

Default model: venice/llama-3.3-70b (good balance of capability + privacy)
Venice API: https://api.venice.ai/api/v1 (OpenAI-compatible)

src/commands/auth-choice-options.ts

@@ -21,6 +21,7 @@ export type AuthChoiceGroupId =
   | "opencode-zen"
   | "minimax"
   | "synthetic"
+  | "venice"
   | "qwen";
 
 export type AuthChoiceGroup = {
@@ -66,6 +67,12 @@ const AUTH_CHOICE_GROUP_DEFS: {
     hint: "Anthropic-compatible (multi-model)",
     choices: ["synthetic-api-key"],
   },
+  {
+    value: "venice",
+    label: "Venice AI",
+    hint: "Privacy-focused (uncensored models)",
+    choices: ["venice-api-key"],
+  },
   {
     value: "google",
     label: "Google",
@@ -190,6 +197,11 @@ export function buildAuthChoiceOptions(params: {
   options.push({ value: "moonshot-api-key", label: "Moonshot AI API key" });
   options.push({ value: "kimi-code-api-key", label: "Kimi Code API key" });
   options.push({ value: "synthetic-api-key", label: "Synthetic API key" });
+  options.push({
+    value: "venice-api-key",
+    label: "Venice AI API key",
+    hint: "Privacy-focused inference (uncensored models)",
+  });
   options.push({
     value: "github-copilot",
     label: "GitHub Copilot (GitHub device login)",