Add auto-slash-command hook for intercepting and replacing slash commands

This hook intercepts user messages starting with '/' and REPLACES them with the actual command template output instead of injecting instructions. The implementation includes:

- Slash command detection (detector.ts) - identifies messages starting with '/'
- Command discovery and execution (executor.ts) - loads templates from ~/.claude/commands/ or similar
- Hook integration (index.ts) - registers with chat.message event to replace output.parts
- Comprehensive test coverage - 37 tests covering detection, replacement, error handling, and command exclusions
- Configuration support in HookNameSchema

Key features:
- Supports excluded commands to skip processing
- Loads command templates from user's command directory
- Replaces user input before reaching the LLM
- Tests all edge cases including missing files, malformed templates, and special commands

🤖 Generated with assistance of OhMyOpenCode (https://github.com/code-yeongyu/oh-my-opencode)

src/hooks/auto-slash-command/detector.ts

@@ -0,0 +1,65 @@
+import {
+  SLASH_COMMAND_PATTERN,
+  EXCLUDED_COMMANDS,
+} from "./constants"
+import type { ParsedSlashCommand } from "./types"
+
+const CODE_BLOCK_PATTERN = /```[\s\S]*?```/g
+
+export function removeCodeBlocks(text: string): string {
+  return text.replace(CODE_BLOCK_PATTERN, "")
+}
+
+export function parseSlashCommand(text: string): ParsedSlashCommand | null {
+  const trimmed = text.trim()
+
+  if (!trimmed.startsWith("/")) {
+    return null
+  }
+
+  const match = trimmed.match(SLASH_COMMAND_PATTERN)
+  if (!match) {
+    return null
+  }
+
+  const [raw, command, args] = match
+  return {
+    command: command.toLowerCase(),
+    args: args.trim(),
+    raw,
+  }
+}
+
+export function isExcludedCommand(command: string): boolean {
+  return EXCLUDED_COMMANDS.has(command.toLowerCase())
+}
+
+export function detectSlashCommand(text: string): ParsedSlashCommand | null {
+  const textWithoutCodeBlocks = removeCodeBlocks(text)
+  const trimmed = textWithoutCodeBlocks.trim()
+
+  if (!trimmed.startsWith("/")) {
+    return null
+  }
+
+  const parsed = parseSlashCommand(trimmed)
+
+  if (!parsed) {
+    return null
+  }
+
+  if (isExcludedCommand(parsed.command)) {
+    return null
+  }
+
+  return parsed
+}
+
+export function extractPromptText(
+  parts: Array<{ type: string; text?: string }>
+): string {
+  return parts
+    .filter((p) => p.type === "text")
+    .map((p) => p.text || "")
+    .join(" ")
+}