fix(bundle): post-merge cleanup follow-ups from #87 (upstream v0.13.0)

[satwareAG-ironMike]

Summary

Post-merge cleanup items from PR #87 review (issue #88). Two minor, non-blocking items, one commit.

Changes

1. src/specify_cli/commands/bundle/__init__.py:829 - reuse hostname local

After the ValueError guard added in upstream v0.13.0, the final host-check re-accessed parsed.hostname instead of reusing the hostname local captured in the try block. The sibling fix in src/specify_cli/presets/__init__.py:2093 already uses the local consistently.

-    if not parsed.hostname:
+    if not hostname:
         raise BundlerError(f"Refusing to download {label} from URL with no host: {url}")

Behavior unchanged (ParseResult is immutable for a given URL, so a successful first access won't raise on re-access). This is a consistency cleanup to prevent drift in future refactors.

2. docs/reference/extensions.md - blank lines for CommonMark block separation

Added blank lines after the closing code fence (line 180) and after the hook-fields table (line 227) in the new "Project Extension and Hook Configuration" section introduced by upstream v0.13.0.

Verification

Acceptance criteria from #88:

• src/specify_cli/commands/bundle/__init__.py:829 uses hostname local
• docs/reference/extensions.md has blank lines after the closing fence (line 180) and after the hook-fields table (line 227)
• Existing bundle tests pass: .venv/bin/python -m pytest tests/unit/test_bundle_download_url.py tests/test_workflows.py -q -> 651 passed, 1 skipped (pre-existing skip)
• Broader regression check: .venv/bin/python -m pytest tests/ --ignore=tests/test_workflows.py -q -> 3783 passed, 113 skipped (pre-existing skips)
• ruff check src/specify_cli/commands/bundle/__init__.py -> All checks passed
• pre-pr privacy check -> clean

Note: the repo's scripts/daily-routine.sh pre-pr reports a failure on the check-upstream-sync.sh step, but that failure is pre-existing on main-speck itself - PR #87 was a squash merge (not a direct tag merge), so v0.13.0's commit SHA is not an ancestor of main-speck. Unrelated to this fix; tracked separately.

Disclosure

Authored and pushed by an AI agent (opencode z-ai/glm-5.2, autonomous) on behalf of @mw. The commit carries the Assisted-by: trailer per the repo's agent disclosure policy.

Closes #88