v0.25.0 — Max-Mode candidate selection + readable board errors

Added

• Execution-grounded Max-Mode candidate selection (ADR 0064) — the loop grounds candidate picks in execution results. (#59)

Fixed

• An unusable board now fails readably instead of cryptically. GET /features and GET /features/{fid} were the only store-touching routes outside _guard — on a board with no repo bound / no .beads / br missing, the BoardError escaped as a text/plain 500 and the console view showed WebKit's SyntaxError: The string did not match the expected pattern. Both routes now answer JSON 400 with the actionable message, and the view's fetch helper surfaces detail (or the HTTP status for non-JSON bodies) instead of a raw parse error — previously a JSON 400 would have silently rendered an empty board. (#60)