chore(deps): update dependencies within semver ranges; hoist ajv@8

npm update refreshed all in-range dev deps. ajv is added as an explicit
devDependency: after the update npm deduped the hoisted ajv-keywords@5
(needs ajv 8) onto the root ajv@6 pulled by eslint, breaking webpack
config validation (Cannot find module 'ajv/dist/compile/codegen');
an explicit ajv@8 at the root nests eslint's ajv@6 instead.

Majors deliberately held: eslint 10 (typescript-eslint peer), typescript 7
(Go-based tsc, separate migration), webpack pinned minor.

Author: eric-mallac