[Chore]: Remove unused open_github_url/_StripAuthOnRedirect from _github_http.py

[PascalThuet]

Update (after #2442 merged main): the original claim that the whole module is dead is no longer accurate. main added resolve_github_release_asset_api_url() to _github_http.py, which is now used by extensions, presets, and workflow URL resolution. The issue is narrowed below to the parts that are genuinely unused.

Problem Statement

src/specify_cli/_github_http.py mixes a live helper with dead code:

• Live: resolve_github_release_asset_api_url() — used by extensions.py, presets.py, and __init__.py (workflow/preset URL resolution).
• Unused in production: open_github_url() (no callers anywhere) and the _StripAuthOnRedirect redirect handler it relies on (referenced only by open_github_url and its tests). build_github_request() / GITHUB_HOSTS are likewise referenced only by tests.

$ git grep -n open_github_url -- 'src/*.py'
src/specify_cli/_github_http.py:...:def open_github_url(...)   # definition only, no callers

The dead _github_http._StripAuthOnRedirect duplicates the live authentication/http._StripAuthOnRedirect: two implementations of the same "strip Authorization on cross-host redirect / reject non-HTTPS redirect" rule, which can drift.

Proposed Solution

Remove the unused open_github_url() and _StripAuthOnRedirect from _github_http.py, keeping the live resolve_github_release_asset_api_url(). Decide whether build_github_request() / GITHUB_HOSTS are worth keeping as a tested utility or should go too. Update tests/test_github_http.py accordingly. No runtime behavior change — the single live redirect/strip-auth path in authentication/http.py is untouched.

Alternatives Considered

Leave as-is: rejected — keeps a second redirect handler alive that a future hardening fix can silently miss.

Component

Specify CLI (initialization, commands)

AI Agent (if applicable)

Not applicable

Use Cases

Maintenance only: one redirect/strip-auth implementation to review and harden instead of two.

Acceptance Criteria

• open_github_url() and its dedicated _StripAuthOnRedirect removed
• resolve_github_release_asset_api_url() retained and still covered by tests
• Decision recorded on build_github_request() / GITHUB_HOSTS (keep as tested utility or remove)
• tests/test_github_http.py updated; full test suite passes

Additional Context

Surfaced during review of #2442. AI disclosure: this issue was drafted and revised by an AI agent (Claude) under my direction; I verified the grep evidence and the current usage of resolve_github_release_asset_api_url after the merge.