Extract sigil-repl library + relocate CLI to (sigil cli repl)

Library/CLI split: (sigil repl) + (sigil repl commands) move to the standalone sigil-repl repo as embeddable REPL infrastructure. The (sigil repl cli) sigil-repl-cli subcommand is absorbed into sigil-cli at (sigil cli repl).

- packages/sigil-repl/: deleted (now standalone at codeberg:sigil/sigil-repl). - packages/sigil-cli/src/sigil/cli/repl.sgl: relocated from packages/ sigil-repl/src/sigil/repl/cli.sgl with its module name renamed to (sigil cli repl). - packages/sigil-cli/src/sigil/cli.sgl: 3 call sites updated for the module rename: optional-command-modules table entry plus two module-exists? checks in usage output. - packages/sigil-cli/package.sgl + packages/sigil-nrepl/package.sgl: swap (from-workspace name: "sigil-repl") to (from-git url: "codeberg:sigil/sigil-repl" version: "^0.13.1"). - Root package.sgl: drop "packages/sigil-repl" from the workspace list. - Root dev-redirects.sgl: add codeberg:sigil/sigil-repl redirect to the sibling task-worktree checkout for monorepo dev. - sigil.lock: add sigil-repl entry pinned to extracted-repo HEAD abcc915709fc3d9915d775a544bd18481e4c88ce (silent-skip workaround pending leader push of codeberg:sigil/sigil-repl).