Migrate conversation search to use PERSONAL_SUPERPOWERS_DIR

Updates conversation indexing and search to use the new personal superpowers
directory structure with environment variable support.

Changes:
- Added src/paths.ts for centralized directory resolution
- Updated db.ts, indexer.ts, verify.ts to use paths.ts
- Created migrate-to-config.sh for data migration from ~/.clank
- Updated all documentation references from ~/.clank to ~/.config/superpowers
- Database paths automatically updated during migration

Migration tested with 5,017 conversations and 6,385 exchanges.

skills/collaboration/remembering-conversations/tool/src/verify.ts

@@ -1,8 +1,8 @@
 import fs from 'fs';
 import path from 'path';
-import os from 'os';
 import { parseConversation } from './parser.js';
 import { initDatabase, getAllExchanges, getFileLastIndexed } from './db.js';
+import { getArchiveDir } from './paths.js';
 
 export interface VerificationResult {
   missing: Array<{ path: string; reason: string }>;
@@ -11,11 +11,6 @@ export interface VerificationResult {
   corrupted: Array<{ path: string; error: string }>;
 }
 
-// Allow overriding paths for testing
-function getArchiveDir(): string {
-  return process.env.TEST_ARCHIVE_DIR || path.join(os.homedir(), '.clank', 'conversation-archive');
-}
-
 export async function verifyIndex(): Promise<VerificationResult> {
   const result: VerificationResult = {
     missing: [],