Add oc session ls|rm, PowerShell login docs, Windows test fix

[Chagas74]

Implements the planned \session ls|rm\ commands and two doc gaps found while adapting oc for a Windows agent setup.

Added

• \oc session ls\ lists saved sessions (name, url, title; --json\ supported,
  o saved sessions\ when empty)
• \oc session rm [name]\ forgets a session — saved page plus cookies, the same promise \oc logout\ makes (defaults to --session, refuses path-like names)
• Tests for ls/rm in \ ests/cli.test.js\ (empty store, listing, rm by name/flag incl. cookie sidecar, invalid name, usage)

Docs

• PowerShell equivalent for cookie login in README + skill (\printf\ does not exist on Windows)
• State location on Windows (%USERPROFILE%\.only-cli, \OC_HOME) in README + skill + \session ls|rm\ in llms.txt
• CHANGELOG entry under Unreleased

Fixed

• Test harness resolves the binary with \ileURLToPath\ (\URL.pathname\ breaks on Windows paths with spaces/drive letters) in cli, cli-auth, distill tests

Validation

• Full suite: 221 pass, 1 fail — the cookies \chmod 0600\ test, which fails identically on a pristine checkout on Windows (pre-existing, untouched by this PR)