Fix the accessibility audit for a deploy status badge

An AI generated a deploy status indicator: a pastel green or red dot with the word Passing or Failing. The pull request screenshot looks polished. But the label barely shows on white, and a screen reader stays silent when the status flips. Your team now runs every status indicator through an audit.

An assistant wrote audit_status_indicator(foreground_hex, background_hex, visible_text, aria_role). It is in the editor. It has a bug. Find it and fix it.

Input and output:

• foreground_hex: the text color, like "#1b5e20".
• background_hex: the background color.
• visible_text: the indicator's visible text.
• aria_role: the element's ARIA role, or "".
• Return the problem codes found, sorted by plain character order. An empty list means the indicator passes.

Rules the tests check:

• "color-only": visible_text is empty after trimming whitespace, so the colored dot is the only cue.
• To parse a color, trim it and drop one leading #. Three hex digits are shorthand, so fff means ffffff. The result must be exactly 6 hex digits: 0 to 9 and a to f, in either case.
• "unknown-color": either color does not parse. Then there is no contrast check.
• "low-contrast": both colors parse and their contrast ratio is below 4.5, the WCAG AA minimum for normal text.
• The contrast ratio follows WCAG 2. For each channel, c is the value divided by 255. Convert it to c / 12.92 when c is at most 0.03928, and otherwise to ((c + 0.055) / 1.055) raised to the power 2.4. A color's luminance is 0.2126 R + 0.7152 G + 0.0722 B, using the converted channels. The ratio is (lighter luminance + 0.05) / (darker luminance + 0.05).
• "not-announced": the role, trimmed and lowercased, is neither status nor alert. Only those roles make a screen reader announce a change.