Migrate to @playcanvas/eslint-config v3 (/typescript)

[kpal81xd]

Part of the v3 rollout — playcanvas/eslint-config#48 (Wave 4).

What changed

• Subpath migration: replaced the v2 default-import spread with the /typescript subpath export.
• Pinned @playcanvas/eslint-config to 3.0.0-beta.6.
• Removed hand-wired @typescript-eslint parser/plugin, the tsPlugin.configs.recommended rules spread, and the import/resolver: { typescript: {} } setting — all now provided by /typescript. Dropped the now-unused @typescript-eslint/eslint-plugin, @typescript-eslint/parser, and eslint-import-resolver-typescript devDeps. Repo-specific **/*.ts browser/serviceworker globals + rule opt-outs and the **/*.mjs node block are preserved; the .mjs import/no-unresolved: off was retargeted to import-x/no-unresolved (v3 uses eslint-plugin-import-x). Dropped the jsdoc/* opt-outs since /typescript does not load the jsdoc plugin.

Lint status

Draft — 371 errors / 5 warnings remain. Strict-mode triage tracked in playcanvas/eslint-config#48; not fixed here per the rollout policy. Note: 2 errors are Definition for rule 'regexp/...' was not found from inline eslint-disable directives in src/ply-sequence.ts and src/file-handler.ts (the regexp plugin was bundled in v2 but is not part of /typescript); left for triage.