Process control for every measurement

The Insights page is now Process Control, rebuilt from scratch.

• Added interactive control charts with spec limits, control limits, histograms, and capability indices (Cp, Cpk, Pp, Ppk) for numeric, string, and boolean measurements
• Added sidebar filters for outcome, value range, retries, and all standard run filters, with a measurement selector sorted by failures, fail rate, or Cpk
• Added measurement table with checkbox selection to drill down into matching runs or units in one click
• Faster loads. Charts and capability indices now compute server-side.