22.5 Editor support

Hanki ships first-party Helix integration: an in-tree tree-sitter grammar (editor/tree-sitter-hanki/), Helix queries (editor/tree-sitter-hanki/queries/helix/), and the hanki lsp / hanki fmt toolchain commands. See [docs/editor/helix.md](docs/editor/helix.md) for the languages.toml snippet and a zero-to-working-setup walkthrough.

The bundled grammar is stale and is a known defect: it predates the current syntax - its only import form is a keyword import the language does not have (§2 has use / open), and it knows nothing of provide, opaque, where, move, async or await - so it does not parse a present-day source file. hanki lsp and hanki fmt are unaffected; only the tree-sitter highlighting is.