feat: Add metadata delete in recce cloud cli

[wcchang1115]

PR checklist

• Ensure you have added or ran the appropriate tests for your PR.
• DCO signed

What type of PR is this?
Feature

What this PR does / why we need it:

• add metadata delete command for recce-cloud cli

Which issue(s) this PR fixes:

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

[Copilot]

Pull request overview

This PR adds delete functionality to the recce-cloud CLI, mirroring the existing download command pattern. The feature supports both platform-specific deletion workflows (GitHub Actions/GitLab CI) and generic session ID-based deletion, with comprehensive test coverage and consistent error handling.

Key changes:

• Adds recce-cloud delete command with --session-id, --prod, --dry-run, and --force options
• Implements platform-specific delete methods for GitHub and GitLab APIs
• Provides comprehensive dry-run tests covering various CI environments

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
recce_cloud/cli.py	Adds new delete command with CI environment detection, dry-run mode, confirmation prompts, and workflow routing logic matching the download command pattern
recce_cloud/delete.py	Implements helper functions delete_existing_session (generic workflow) and delete_with_platform_apis (CI/CD workflow) following the same structure as download.py
recce_cloud/api/base.py	Adds abstract delete_session method to the base platform client interface
recce_cloud/api/client.py	Implements delete_session method for the generic RecceCloudClient with proper error handling for 204, 403, and 404 responses
recce_cloud/api/github.py	Adds delete_session method for GitHub platform client using DELETE /api/v2/github/{repo}/session endpoint with PR number or base parameter
recce_cloud/api/gitlab.py	Adds delete_session method for GitLab platform client using DELETE /api/v2/gitlab/{project}/session endpoint with MR IID or base parameter
tests/recce_cloud/test_client.py	Adds unit tests for RecceCloudClient.delete_session covering success (204), not found (404), forbidden (403), and server error (500) cases
tests/recce_cloud/test_platform_clients.py	Adds unit tests for GitHub and GitLab platform clients covering CR session deletion, prod session deletion, and parameter handling
tests/recce_cloud/test_cli.py	Adds comprehensive dry-run tests for delete command covering GitHub Actions, GitLab CI (both cloud and self-hosted), prod flag, session ID workflow, and warning messages