BlindTerm v0.7.4

BlindTerm v0.7.4 fixes commands typed at agent CLIs not being sent, and starts the same program a shell would when two tools share a name.

• What you type at an agent CLI now gets sent. Codex counted a whole line arriving in one write as a paste, and a Return inside a paste is a newline rather than "send this": typing "test" and pressing Enter put the word in Codex's composer, added a blank line under it, and sent nothing, forever. BlindTerm now leaves the Return long enough after the line to be unmistakably a keypress whenever a program rather than a shell prompt is reading it. A MUD is unaffected -- nothing on the far end of a connection guesses at pasting, and commands there are still sent at once.
• The same program a shell would run starts when two tools share a name. The search for a command went extension by extension -- every directory on PATH for a .exe, then every directory for a .cmd -- so an unrelated opencode.exe further down PATH beat the opencode shim that every shell runs. It printed a usage error and exited before anything could be typed at it. The search now goes directory by directory, the way a shell does.
• PowerShell scripts run. A .ps1 typed by name or by path now runs through PowerShell 7, or Windows PowerShell where 7 is not installed, the way .cmd and .bat files already ran through cmd.exe. Named by itself it is found even though the stock PATHEXT never mentions .PS1, because that is what happens at a PowerShell prompt.

Verification: 851 automated tests pass with zero warnings, 10 of them new -- 6 for command resolution and 4 for the submit gap. The portable archive and installer are self-contained Windows x64 builds, and SHA-256 hashes are published in BlindTerm-update.json.