feat: add nameserver management

[cosmin]

Add support for setting and querying custom nameservers for domains.

Library API:

• nc.dns.set_custom_nameservers(domain, nameservers) - switch to custom NS
• nc.dns.set_default_nameservers(domain) - reset to Namecheap BasicDNS
• nc.dns.get_nameserver_info(domain) - get current NS configuration

CLI commands:

• namecheap-cli dns set-nameservers ...
• namecheap-cli dns reset-nameservers
• namecheap-cli dns nameservers

[Copilot]

Pull request overview

This PR adds support for managing custom nameservers for domains through both the library API and CLI commands. The implementation allows users to switch between Namecheap's default BasicDNS and custom nameservers (e.g., Route 53, Cloudflare).

Changes:

• Added three new DNS API methods: set_custom_nameservers(), set_default_nameservers(), and get_nameserver_info()
• Added three new CLI commands: nameservers, set-nameservers, and reset-nameservers
• Updated pending.md to document the newly implemented nameserver management features

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
src/namecheap/_api/dns.py	Adds three API methods for managing domain nameservers - setting custom nameservers, resetting to defaults, and querying current configuration
src/namecheap_cli/main.py	Implements three CLI commands for nameserver management with confirmation prompts, progress indicators, and formatted output
pending.md	Documents the implemented nameserver management functionality and marks it as complete

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[Copilot]

The handling of ns_data does not account for all possible types returned by the API. While the code handles string and list types, if ns_data is a dict or another type (which can occur with certain XML parsing edge cases), nameservers will remain an empty list without any indication of the issue. Consider adding an else clause to handle unexpected types or log a warning, for example: else: logger.warning(f"Unexpected nameserver data type: {type(ns_data)}")

[adriangalilea]

Hey @cosmin, thanks for the contribution!

I pushed a cleanup commit on top of your branch. Here's what I changed:

• get_nameserver_info() → get_nameservers() — shorter, return type already says it's info
• Returns a Nameservers Pydantic model (is_default: bool, nameservers: list[str]) instead of dict[str, Any] — consistent with how every other method in the SDK uses models
• Replaced the silent fallback (if not result: return {…}) with an assert — if the API returns nothing, that's unexpected and we want to know
• Replaced isinstance branching with assert + ternary
• Replaced ValueError with assert for nameserver count/emptiness validation in set_custom_nameservers
• Removed noise comments (# Parse domain, # Extract nameservers)
• Added nameserver management section to README
• Version bump to 1.1.0

Tested against live domains, everything works. Appreciate the PR!