chore: update package version and types path; refactor endpoint fetching logic

- Bump version from 1.5.0 to 1.6.0 in package.json
- Change types path in package.json to point to src/index.d.ts
- Refactor getContentstackEndpoint function to use local regions data
- Add error handling for invalid regions and services
- Implement helper functions for default endpoint retrieval and region lookup

Author: nadeem-cs

.gitignore

@@ -15,4 +15,5 @@ dist/
 coverage/
 .dccache
 snyk_output.log
-talisman_output.log
+talisman_output.log
+regions.json

.talismanrc

@@ -3,7 +3,7 @@ fileignoreconfig:
   ignore_detectors:
     - filecontent
 - filename: package-lock.json
-  checksum: 9746d3b1ac67da5dc0f3ec6f8798166bc8b9c1e4c736de01f7c52b2f9cc194be
+  checksum: b02ba32eb9fae068f91a1c3604582388ca67e3d735dd5d241d58cab085e89382
 - filename: src/entry-editable.ts
   checksum: f9c4694229205fca252bb087482a3e408c6ad3b237cd108e337bcff49458db5c
 - filename: .husky/pre-commit