chore: promote no-explicit-any from warn to error (#12244)

* chore: promote no-explicit-any from warn to error and resolve violations

Upgrades the oxlint rule severity and removes all 40 existing
`no-explicit-any` warnings across the codebase. Most call sites gained
proper types (SharedEditor refs, JSONNode/JSONMark for ProseMirror JSON
walking, DocumentsStore, dd-trace `Span` parameter inference, prosemirror
Fragment public API in place of internal `(fragment as any).content`).
A few load-bearing `any` uses were preserved with scoped disable
comments where changing the type would cascade widely (Sequelize JSONB
columns on `Event`, the `withTracing` higher-order function generic,
`Extension.options` consumed by many subclasses, dd-trace's `req`
patching).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.oxlintrc.json

@@ -31,7 +31,7 @@
     "no-empty-pattern": "error",
     "no-empty-static-block": "error",
     "no-ex-assign": "error",
-    "no-explicit-any": "warn",
+    "no-explicit-any": "error",
     "no-extra-boolean-cast": "error",
     "no-fallthrough": "error",
     "no-func-assign": "error",