feat(login): randomize Russian welcome headlines

PLANS.md

@@ -1114,7 +1114,7 @@ manner of Docker's random container names.
 
 ## Milestone 013 — Random humorous login headlines
 
-**Status:** `NOT_STARTED`
+**Status:** `COMPLETE`
 
 ### Objective
 
@@ -1155,7 +1155,21 @@ headline at random whenever a player opens the page.
 
 ### Evidence
 
-Completion evidence is not yet available. Expected evidence includes targeted
-browser-test output, `bash scripts/run_host_tests.sh`, and the reproducible
-web-asset size and hash report from
-`/home/sasa/.platformio/penv/bin/pio run -e esp32-c6-devkitm-1 --target buildfs`.
+- The browser test `login headline selection is randomizable, Russian, and has
+  a fallback` passed. It verifies eight locally authored, appropriate Russian
+  two-line headlines, deterministic injected selection, fallback to the first
+  valid headline for an invalid source, and initialization-time rendering into
+  the existing heading structure.
+- `node --check web/player.js` and `bash scripts/run_host_tests.sh` passed. The
+  full host suite reported ten browser tests and web-asset reproducibility with
+  SHA-256 `ca5a637087748707367bd6ccec7885d0ff6ad20bd4713df528403e13f26fa540`
+  using 20,281 of 1,572,864 allowed compressed bytes.
+- `pio run -e esp32-c6-devkitm-1 --target buildfs` passed; its LittleFS image
+  uses 2,031,616 of 2,031,616 partition bytes. The layout preserves the
+  existing `h1`, line break, and highlighted span, so no responsive or
+  accessibility structure changed.
+- Each login-page initialization selects its headline through the bounded
+  browser-random helper. Strong browser randomness is preferred, and the
+  helper falls back safely when unavailable. This satisfies every Milestone 013
+  acceptance criterion. Milestone 013 is `COMPLETE`; Milestone 014 remains
+  `NOT_STARTED`.