fix(llms): require a fully-qualified base URL for link rewriting

[neon60]

Motivation

_resolve_base_url accepted any truthy candidate, so a scheme-less html_baseurl such as "instinct.docs.amd.com" was emitted verbatim, producing malformed links like "instinct.docs.amd.com/page.html" in llms.txt and llms-full.txt. Validate each candidate with urlparse and use it only when it has both a scheme and a netloc; otherwise warn and fall back to relative links.

Technical Details

• In src/rocm_docs/llms.py, _resolve_base_url now parses each candidate (rocm_docs_llms_base_url → html_baseurl → READTHEDOCS_CANONICAL_URL) with urllib.parse.urlparse and only accepts it when both scheme and netloc are present (e.g. https://example.com).
• A candidate that is present but not fully-qualified (e.g. instinct.docs.amd.com) is skipped with a logger.warning, and resolution continues to the next candidate — ultimately falling back to relative links (page.html) rather than emitting a malformed absolute link.
• No behavior change on Read the Docs: RTD sets READTHEDOCS_CANONICAL_URL to a fully-qualified https:// URL, which passes validation and continues to produce correct absolute links. The fix only affects builds where the resolved base URL lacks a scheme (typically local/non-RTD builds using a scheme-less html_baseurl default).- Added from urllib.parse import urlparse import.

Test Plan

• Added three unit tests in tests/test_llms.py exercising _resolve_base_url directly:
  • a fully-qualified URL is accepted (and trailing slash stripped),
  • a scheme-less value is rejected, falling back to "" (relative links),
  • a scheme-less higher-priority candidate is skipped in favor of a valid lower-priority one.
• Ran the full tests/test_llms.py suite to confirm no regression (the existing absolute-URL test uses a valid https:// base and must still pass).
• End-to-end validation against a real consumer: built the system-acceptance-docs site (which has a scheme-less html_baseurl default) with this patched generator and inspected the generated llms.txt/llms-full.txt.

Test Result

• Unit tests: 22 passed (19 existing + 3 new) in tests/test_llms.py, no regressions.
• End-to-end build succeeded and logged the new warning: llms: ignoring base URL 'instinct.docs.amd.com' because it is not a fully-qualified URL (needs a scheme, e.g. https://); internal links will be relative. Generated links changed from the malformed AMD Instinct MI355X to the valid relative AMD Instinct MI355X.

Submission Checklist

• Look over the contributing guidelines at https://github.com/ROCm/ROCm/blob/develop/CONTRIBUTING.md#pull-requests.