FleetdLeadConfigDirSourceWiringTest already pins Fleetd.leadConfigDirSource
itself, but by its own javadoc cannot cover whether FleetdAssembly.java:488
still calls it -- that call site could be swapped for a bare
FleetMcp.LeadConfigDirSource.none() (the literal fleetd #602/#606 defect)
and the whole suite would stay green.
Add FleetdLeadConfigDirSourceAssemblyTest: assembles the real FleetdRuntime
via FleetdAssembly.assembleAndStart, reads the leadConfigDirs field off the
real FleetMcp via reflection (no public accessor exists), and asserts it
resolves a configured lead's real configDir rather than none()'s hardcoded
null.
Verified: loud control (flip expected value) goes RED, reverts green;
mutation (i) inert none() at the call site goes RED; mutation (ii) mis-wire
(empty profile map, symbols otherwise intact) goes RED; both mutations
revert to an empty git diff. Full mvn clean install: 1893 tests, 0
failures, 0 errors, BUILD SUCCESS.