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>

examples/13-hooks.ts

@@ -0,0 +1,88 @@
+/**
+ * Example 13: Hooks
+ *
+ * Shows how to use lifecycle hooks to intercept agent behavior.
+ * Hooks fire at key points: session start/end, before/after tool use,
+ * compaction, etc.
+ *
+ * Run: npx tsx examples/13-hooks.ts
+ */
+import { createAgent, createHookRegistry } from '../src/index.js'
+import type { HookInput } from '../src/index.js'
+
+async function main() {
+  console.log('--- Example 13: Hooks ---\n')
+
+  // Create a hook registry with custom handlers
+  const registry = createHookRegistry({
+    SessionStart: [{
+      handler: async (input: HookInput) => {
+        console.log(`[Hook] Session started: ${input.sessionId}`)
+      },
+    }],
+    PreToolUse: [{
+      handler: async (input: HookInput) => {
+        console.log(`[Hook] About to use tool: ${input.toolName}`)
+        // You can block a tool by returning { block: true }
+        // return { block: true, message: 'Tool blocked by hook' }
+      },
+    }],
+    PostToolUse: [{
+      handler: async (input: HookInput) => {
+        const output = typeof input.toolOutput === 'string'
+          ? input.toolOutput.slice(0, 100)
+          : JSON.stringify(input.toolOutput).slice(0, 100)
+        console.log(`[Hook] Tool ${input.toolName} completed: ${output}...`)
+      },
+    }],
+    PostToolUseFailure: [{
+      handler: async (input: HookInput) => {
+        console.log(`[Hook] Tool ${input.toolName} FAILED: ${input.error}`)
+      },
+    }],
+    Stop: [{
+      handler: async () => {
+        console.log('[Hook] Agent loop completed')
+      },
+    }],
+    SessionEnd: [{
+      handler: async () => {
+        console.log('[Hook] Session ended')
+      },
+    }],
+  })
+
+  // Create agent with hook registry
+  // Note: For direct HookRegistry usage, we pass hooks via the engine config.
+  // The AgentOptions.hooks format also works (see below).
+  const agent = createAgent({
+    model: process.env.CODEANY_MODEL || 'claude-sonnet-4-6',
+    maxTurns: 5,
+    // Alternative: use AgentOptions.hooks format
+    hooks: {
+      PreToolUse: [{
+        hooks: [async (input: any, toolUseId: string) => {
+          console.log(`[AgentHook] PreToolUse: ${input.toolName} (${toolUseId})`)
+        }],
+      }],
+    },
+  })
+
+  for await (const event of agent.query('What files are in the current directory? Be brief.')) {
+    const msg = event as any
+    if (msg.type === 'assistant') {
+      for (const block of msg.message?.content || []) {
+        if (block.type === 'text' && block.text.trim()) {
+          console.log(`\nAssistant: ${block.text.slice(0, 200)}`)
+        }
+      }
+    }
+    if (msg.type === 'result') {
+      console.log(`\n--- ${msg.subtype} ---`)
+    }
+  }
+
+  await agent.close()
+}
+
+main().catch(console.error)