## Problem
After the initial submit hardening, two issues remained: source code was
read in Lua and piped as stdin to the scraper (unnecessary roundtrip
since
the file exists on disk), and CF's `page.fill()` timed out on the hidden
`textarea[name="source"]` because CodeMirror owns the editor state.
## Solution
Pass the source file path as a CLI arg instead — AtCoder calls
`page.set_input_files(file_path)` directly, CF reads it with
`Path(file_path).read_text()`. Fix CF source injection via
`page.evaluate()`
into the CodeMirror instance. Extract `BROWSER_SUBMIT_NAV_TIMEOUT` as a
per-platform `defaultdict` (CF defaults to 2× nav timeout). Save the
buffer
with `vim.cmd.update()` before submitting.
Add stress.lua that auto-detects or accepts generator and brute solution
files, compiles C++ if needed, and launches scripts/stress.py in a
terminal buffer with session save/restore and cleanup autocmds.
Add scripts/stress.py as a standalone loop that runs generator → brute →
candidate, comparing outputs and exiting on the first mismatch.
