Sweep monorepo packages: declare sigil: ^0.13

Every in-monorepo packages/*/package.sgl now declares the Sigil-language version range it supports. ^0.13 is the active stable minor — these all built and shipped in the 0.13.x line.

Field placed immediately after name: (no version: line in any in-monorepo package — they all inherit version from the workspace, so "after version:" reduces to "after name:" in practice).

Workspace root package.sgl is intentionally left alone: it's a (workspace ...) form, not a (package ...). Workers and the CLI's validation walker iterate workspace-packages and check each member package for sigil:; the workspace itself doesn't declare a Sigil version.

Extracted libraries (sigil-test, sigil-mcp, sigil-lsp, sigil-json, etc.) are not swept here — that's Step 2 of the 0.14.0 redesign (folds into t-dc5d). Tightening transitive-dep validation before they declare sigil: would break monorepo builds.