fix(docker): carry the owned flag on the wire the way master already does

The cherry-picked "copy an existing case" commit declared a second
`CaseInfo.docker.owned` and emitted `owned: true|false` on every docker
case, while master had meanwhile shipped the same field from the
adopted-container work with a narrower wire shape: `owned` is present
only when false, absent means owned. Two declarations failed typecheck,
and two emit styles on one response would have made the picker's answer
depend on which read path filled it.

Keep master's shape at both response sites (the case list and the
single-case lookup, which lacked the field entirely), fold the picker's
reason for the field into the existing doc comment, and repoint the test
that pinned "set on exactly two sites" at the surviving form, adding a
negative pin so the duplicate style cannot come back.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

src/web/routes/case-routes.ts

@@ -329,7 +329,6 @@ export function registerCaseRoutes(app: FastifyInstance, ctx: EventPort & Config
           image: host.image,
           path: dockerCase.hostWorkspacePath,
           containerWorkdir: dockerCase.containerWorkdir ?? dockerCase.hostWorkspacePath,
-          owned: dockerCase.owned !== false,
           network: host.network ?? 'bridge',
           ...(dockerCase.availableModes ? { availableModes: dockerCase.availableModes } : {}),
           ...(dockerCase.owned === false ? { owned: false } : {}),
@@ -1610,8 +1609,8 @@ export function registerCaseRoutes(app: FastifyInstance, ctx: EventPort & Config
           image: host.image,
           path: dockerCase.hostWorkspacePath,
           containerWorkdir: dockerCase.containerWorkdir ?? dockerCase.hostWorkspacePath,
-          owned: dockerCase.owned !== false,
           network: host.network ?? 'bridge',
+          ...(dockerCase.owned === false ? { owned: false } : {}),
         },
       };
     }