Run and unit metadata added to the framework

High-value units are often tested while undergoing modifications, and standard identifiers like revision number can't capture that state — custom metadata now records it on every run and unit.

• Added run.metadata and unit.metadata to the Python phase API, validated at assignment with clear errors and included even when a phase fails
• Added operator-prompted unit metadata fields to the procedure file, rendered in the unit identification form next to the serial number
• Added metadata to uploaded reports and Studio local reports so runs and units can be filtered by any key