fix: three errors that ended with the wrong exit code

Found compiling the environment-variable table for AGENTS.md:
- A REVIEW_GATES_MEM_RESERVE_MB that is no number threw
  std::invalid_argument, which nothing caught: the process aborted where
  it should end with a ValueError, exit 1. nan and inf were an unchecked
  cast. They raise ValueError / OverflowError now; a value past int64
  saturates.
- An env file that is not UTF-8: `run` ended with exit 1 where its
  preflight should stop it (exit 3), and `seats` parsed the raw bytes. Both
  read it as strict UTF-8 text now.
- A broker address with a port past 65535 was cut to 16 bits; it is an
  OverflowError now, uncaught (exit 1).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

implementations/Crafter.Review-Driver.cpp

@@ -515,9 +515,9 @@ inventory unit, against a frozen commit range.)";
             if (envFile.empty() && fs::exists(".env", error)) envFile = ".env";
             std::map<std::string, std::string> env = process;
             if (!envFile.empty()) {
-                const std::optional<std::string> text = Platform::ReadFile(envFile);
-                if (!text) throw Dyn::Error("FileNotFoundError", std::format("[Errno 2] No such file or directory: {}", Dyn::Repr(envFile)));
-                for (const auto& [name, value] : Seats::SeatTokensFromEnvFile(*text)) env[name] = value;
+                // The env file, read as text: one that cannot be read, or is not
+                // UTF-8, ends the command.
+                for (const auto& [name, value] : Seats::SeatTokensFromEnvFile(Dyn::ReadText(envFile))) env[name] = value;
             }
             std::vector<SeatJob> jobs;
             for (const auto& [seat, token] : Seats::SeatTokensFromEnv(env)) jobs.push_back({seat, token, false});