Interview Prep: mock interview mode + accuracy pass

Two updates to the Interview Preparation tool. Mock interview mode — a new Start mock interview button at the top of the tool draws 10 random questions from whatever's applicable to your current profile and walks you through them one at a time. Try to answer out loud, then reveal the framework, then mark each one as known or not yet. At the end you get a tally and can run another round. Anything you mark as not yet is a good candidate for bookmarking and coming back to. Accuracy pass — some specific corrections to the technical content so the senior interview answers stand up to scrutiny. API RP 53 references now show as API STD 53 (5th Edition, 2018) with the older RP designation noted for legacy familiarity. The IOGP Life Saving Rules flashcard now lists the correct 9 consolidated rules from the 2018 update rather than older wording. H2S alarm thresholds are qualified as operator-specific (PDO and ADNOC use 1 ppm in many occupied areas) rather than presented as an industry default. The gas migration explanation has a brief footnote that the strict thermodynamics uses the combined gas law (PV=nRT), with Boyle's Law given as the everyday approximation.