feat: add skills system, hooks integration, and OpenAI-compatible provider

- Add skill system with types, registry, SkillTool, and 5 bundled skills
  (simplify, commit, review, debug, test)
- Integrate hooks into QueryEngine at 9 lifecycle points (SessionStart,
  UserPromptSubmit, PreToolUse, PostToolUse, PostToolUseFailure,
  PreCompact, PostCompact, Stop, SessionEnd)
- Add LLM provider abstraction supporting both Anthropic Messages API
  and OpenAI Chat Completions API (works with GPT, DeepSeek, Qwen, etc.)
- Add CODEANY_API_TYPE env var ('anthropic-messages' | 'openai-completions')
  with auto-detection from model name
- Remove all ANTHROPIC_* env var references, only support CODEANY_* prefix
- Add model pricing and context windows for OpenAI/DeepSeek models
- Remove direct @anthropic-ai/sdk dependency from all files except the
  Anthropic provider (types.ts, engine.ts, etc. are now provider-agnostic)
- Add PermissionBehavior type export
- Bump version to 0.2.0

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/providers/anthropic.ts

@@ -0,0 +1,60 @@
+/**
+ * Anthropic Messages API Provider
+ *
+ * Wraps the @anthropic-ai/sdk client. Since our internal format is
+ * Anthropic-like, this is mostly a thin pass-through.
+ */
+
+import Anthropic from '@anthropic-ai/sdk'
+import type {
+  LLMProvider,
+  CreateMessageParams,
+  CreateMessageResponse,
+} from './types.js'
+
+export class AnthropicProvider implements LLMProvider {
+  readonly apiType = 'anthropic-messages' as const
+  private client: Anthropic
+
+  constructor(opts: { apiKey?: string; baseURL?: string }) {
+    this.client = new Anthropic({
+      apiKey: opts.apiKey,
+      baseURL: opts.baseURL,
+    })
+  }
+
+  async createMessage(params: CreateMessageParams): Promise<CreateMessageResponse> {
+    const requestParams: Anthropic.MessageCreateParamsNonStreaming = {
+      model: params.model,
+      max_tokens: params.maxTokens,
+      system: params.system,
+      messages: params.messages as Anthropic.MessageParam[],
+      tools: params.tools
+        ? (params.tools as Anthropic.Tool[])
+        : undefined,
+    }
+
+    // Add extended thinking if configured
+    if (params.thinking?.type === 'enabled' && params.thinking.budget_tokens) {
+      (requestParams as any).thinking = {
+        type: 'enabled',
+        budget_tokens: params.thinking.budget_tokens,
+      }
+    }
+
+    const response = await this.client.messages.create(requestParams)
+
+    return {
+      content: response.content as CreateMessageResponse['content'],
+      stopReason: response.stop_reason || 'end_turn',
+      usage: {
+        input_tokens: response.usage.input_tokens,
+        output_tokens: response.usage.output_tokens,
+        cache_creation_input_tokens:
+          (response.usage as any).cache_creation_input_tokens,
+        cache_read_input_tokens:
+          (response.usage as any).cache_read_input_tokens,
+      },
+    }
+  }
+}