fix: preserve task prompts as free text

[Epochex]

Summary

• stop re-tokenizing a task's sole free-text argument as a command line
• keep runtime flags separate from prompt content with an explicit -- boundary
• preserve multiline text, quotes, Windows paths, and flag-looking prose verbatim
• update the rescue-agent contract and CLI usage to use the safe invocation shape

Fixes #512.

Root cause

normalizeArgv() treated every single argument as a raw command line. For task prompts, this fed user prose through shell-style quote/backslash removal and then through option parsing. Text such as --model or --write could therefore change runtime behavior instead of reaching Codex, while Windows paths, quotes, and newlines were silently corrupted.

The compatibility behavior remains in place for commands that receive Claude Code's quoted $ARGUMENTS; only task, whose positional payload is free text, opts out.

Impact

Codex rescue tasks now receive the exact prompt Claude Code forwarded. Prompts about CLIs can safely contain option names, and Windows paths and quoted diagnostics are no longer mangled. Explicit task controls still work before --.

Validation

• node --test tests/*.test.mjs under Linux / Node 22.23.1: 93 passed, 0 failed
• node_modules/.bin/tsc.cmd -p tsconfig.app-server.json
• git diff --check