Add issue create command to the CLI

[hex2dec]

Problem

The CLI supports issue list, issue view, and issue comment, but it does not support creating issues. This leaves issue authoring incomplete compared with the existing read and comment workflows.

Root Cause Analysis

Issue support currently stops at read and comment operations. The command surface, service layer, API integration, and integration coverage do not include issue creation, so the CLI has no public path for authoring a new issue.

Fix Plan

1. Add an issue create command to the CLI surface.
2. Implement issue creation in the service layer and Gitee API client.
3. Reuse existing repository-context resolution so the command works both with --repo and inside a local checkout.
4. Reuse existing body input patterns so issue creation supports inline body text, file input, and stdin where appropriate.
5. Keep output and error handling aligned with the existing CLI conventions.

Acceptance Criteria

• issue create is available from the CLI.
• The command supports stable text and JSON output.
• The command supports authentication and local repository inference.
• The command supports the expected title/body input flows.
• Error handling remains consistent with the rest of the CLI.
• All new tests pass.
• Existing tests still pass.