R-977: a new FileBrowser run is given ~20 s to answer in the same tick

rc.1 on 9202: the tick that brought FileBrowser back probed it while it was starting; the default login stayed
open for one 5-minute round. TestFileBrowserAdmin_R977_NewRunIsWaitedForInTheSameTick, red-proved.

Claude-Session: https://claude.ai/code/session_0159rPz1ZhFKsS53msqPYxtS

CHANGELOG.md

@@ -8,8 +8,10 @@
   (the container's StartedAt), not once per box. Measured first on scratch 9202 with 0.324.0: FileBrowser and its data
   volume removed, the box brought it back on its own — the default login answered 200 while the box kept its old
   „generated" record. Now such a run is reset at its first tick (a generated password, verified both ways, stored
-  encrypted); a run on any other password — the household's own — changes nothing. `TestFileBrowserAdmin_R977_*`,
-  red-proved (the old once-per-box return keeps the default). The code comment „before a claim there is no tunnel"
+  encrypted); a run on any other password — the household's own — changes nothing. A NEW run is given ~20 s to answer
+  in the same tick (rc.1 on 9202: the tick that brought FileBrowser back probed it while it was starting, and the
+  default stayed open for one whole 5-minute round). `TestFileBrowserAdmin_R977_*` (2), each red-proved (the old
+  once-per-box return keeps the default; one try per tick leaves it open). The code comment „before a claim there is no tunnel"
   was false (the claim is reached through the tunnel) and is corrected; the tunnel itself is NOT changed — R-1120.
 - **R-1116** — the decoy suite is a gate of the full run (below, the helper's note).