fix: honor CLAUDE_CONFIG_DIR environment variable (#261)

Fixes #255

- Add getClaudeConfigDir() utility function that respects CLAUDE_CONFIG_DIR env var
- Update all hardcoded ~/.claude paths to use the new utility
- Add comprehensive tests for getClaudeConfigDir()
- Maintain backward compatibility with default ~/.claude when env var is not set

Files updated:
- src/shared/claude-config-dir.ts (new utility)
- src/shared/claude-config-dir.test.ts (tests)
- src/hooks/claude-code-hooks/config.ts
- src/hooks/claude-code-hooks/todo.ts
- src/hooks/claude-code-hooks/transcript.ts
- src/features/claude-code-command-loader/loader.ts
- src/features/claude-code-agent-loader/loader.ts
- src/features/claude-code-skill-loader/loader.ts
- src/features/claude-code-mcp-loader/loader.ts
- src/tools/session-manager/constants.ts
- src/tools/slashcommand/tools.ts

Co-authored-by: sisyphus-dev-ai <sisyphus-dev-ai@users.noreply.github.com>

src/shared/claude-config-dir.test.ts

@@ -0,0 +1,60 @@
+import { describe, test, expect, beforeEach, afterEach } from "bun:test"
+import { homedir } from "node:os"
+import { join } from "node:path"
+import { getClaudeConfigDir } from "./claude-config-dir"
+
+describe("getClaudeConfigDir", () => {
+  let originalEnv: string | undefined
+
+  beforeEach(() => {
+    originalEnv = process.env.CLAUDE_CONFIG_DIR
+  })
+
+  afterEach(() => {
+    if (originalEnv !== undefined) {
+      process.env.CLAUDE_CONFIG_DIR = originalEnv
+    } else {
+      delete process.env.CLAUDE_CONFIG_DIR
+    }
+  })
+
+  test("returns CLAUDE_CONFIG_DIR when env var is set", () => {
+    process.env.CLAUDE_CONFIG_DIR = "/custom/claude/path"
+    
+    const result = getClaudeConfigDir()
+    
+    expect(result).toBe("/custom/claude/path")
+  })
+
+  test("returns ~/.claude when env var is not set", () => {
+    delete process.env.CLAUDE_CONFIG_DIR
+    
+    const result = getClaudeConfigDir()
+    
+    expect(result).toBe(join(homedir(), ".claude"))
+  })
+
+  test("returns ~/.claude when env var is empty string", () => {
+    process.env.CLAUDE_CONFIG_DIR = ""
+    
+    const result = getClaudeConfigDir()
+    
+    expect(result).toBe(join(homedir(), ".claude"))
+  })
+
+  test("handles absolute paths with trailing slash", () => {
+    process.env.CLAUDE_CONFIG_DIR = "/custom/path/"
+    
+    const result = getClaudeConfigDir()
+    
+    expect(result).toBe("/custom/path/")
+  })
+
+  test("handles relative paths", () => {
+    process.env.CLAUDE_CONFIG_DIR = "./my-claude-config"
+    
+    const result = getClaudeConfigDir()
+    
+    expect(result).toBe("./my-claude-config")
+  })
+})

src/shared/claude-config-dir.ts

@@ -0,0 +1,11 @@
+import { homedir } from "node:os"
+import { join } from "node:path"
+
+export function getClaudeConfigDir(): string {
+  const envConfigDir = process.env.CLAUDE_CONFIG_DIR
+  if (envConfigDir) {
+    return envConfigDir
+  }
+  
+  return join(homedir(), ".claude")
+}

src/shared/index.ts

@@ -13,3 +13,4 @@ export * from "./dynamic-truncator"
 export * from "./config-path"
 export * from "./data-path"
 export * from "./config-errors"
+export * from "./claude-config-dir"