fix(git): support git@ SSH URLs with regression-safe repo detection (#317)

[r266-tech]

Description

Fix CLI's inability to recognize git@domain:repo.git format URLs (Issue #317).

This PR takes a different approach from #375 by introducing a strict is_git_repo_url() function that prevents the regression identified by @qin-ctx — HTTPS URLs like https://github.com/org/repo/issues/123 are correctly not routed to CodeRepositoryParser.

Related Issue

Fixes #317

Key Design Decisions

Regression-safe routing via is_git_repo_url()

• git@, ssh://, git:// protocols → always treated as git repos (if domain matches)
• https:// URLs → only treated as repos when path has exactly 2 segments (/owner/repo)
• URLs with sub-paths like /issues/, /pull/, /blob/ are not routed to git clone

Addresses all review comments from PR #375

1. Regression risk (media_processor routing): Fixed with is_git_repo_url() strict path check
2. Error message command info lost (_run_git): Preserved with Command: git {args}. Details: {error}
3. No tests: Added 20 comprehensive pytest tests
4. SSH/HTTP path inconsistency: Both branches now take only first 2 path segments
5. Unnecessary try/except: Removed, uses explicit return False

Changes Made

File	Change
code_hosting_utils.py	Added git@ support to parse_code_hosting_url, is_code_hosting_url; new validate_git_ssh_uri, is_git_repo_url
__init__.py	Export new functions
media_processor.py	Recognize git URLs in _is_url(); route to CodeRepositoryParser in _process_url()
resources.py	CLI recognizes git@/ssh://git:// as URLs
code.py	Handle git@ in parse(); enhanced error messages with command info
test_code_hosting_utils.py	20 tests covering all new functions

Testing

$ python3 -m pytest tests/test_code_hosting_utils.py -v
20 passed in 0.27s

Test coverage includes:

• git@github.com:org/repo.git → correctly parsed as org/repo
• git@unknown.com:org/repo.git → rejected (unknown domain)
• git@github.com:repo → rejected (single segment)
• https://github.com/org/repo → recognized as repo
• https://github.com/org/repo/issues/123 → NOT a repo (regression test)
• https://github.com/org/repo/pull/456 → NOT a repo (regression test)
• https://github.com/org/repo/blob/main/file.py → NOT a repo (regression test)
• Validation: empty path, missing colon, non-git URI → ValueError

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