UR-Nexus 1.67.0

• Two subsystems loaded behind feature flags were not merely disabled, they
  were broken in a way that only showed if you enabled them.
  services/compact/reactiveCompact.ts did not exist on disk at all, yet
  query.ts requires it by path and /compact calls two functions on it;
  services/contextCollapse/index.ts was a stub exporting four names while
  query.ts called four different ones, three of which were absent. Setting
  either flag would have failed on the first turn with MODULE_NOT_FOUND or
  "is not a function" rather than degrading to "feature off". Both modules now
  export the full surface their callers use, returning result-shaped objects
  instead of null so property access on the result cannot throw.
• Neither was reachable in shipped builds — the bundler passes only VOICE_MODE
  and CHICAGO_MCP, and live context management runs through
  services/compact/autoCompact.ts, which is real and unaffected.
• Added test/optionalSubsystems.test.ts, which derives the required exports
  from what query.ts actually calls rather than from a hand-written list, so
  a new call site cannot reintroduce the gap. It also asserts autoCompact has
  not itself become a stub.
• Audit note: 223 files carry @ts-nocheck and are invisible to
  tsc --noEmit. Stripping the suppressions in a scratch copy surfaces 872
  errors across ~108k lines, including query.ts, permissions.ts and
  filesystem.ts. Both defects above sat inside that blind spot.