fix(ts-migration): clear the last six pre-existing type errors

These six pre-date the migration. They were unfixable while the files
holding them were JavaScript with `checkJs`, because the fix in each case
is an annotation JSDoc cannot express. `src/` is TypeScript now, so:

  - `setWidthState.timer` in `AssistantPanelContext` is a debounce handle
    hung on the callback itself, so it survives re-renders without a ref.
    TypeScript has no way to describe an expando on a `useCallback`
    result, so the binding is `any`.
  - `runAction(name, { skill, ...payload } = {})` — the `= {}` default
    types the parameter `{}`, so reading `skill` off it looked wrong.
  - `Progression` in `Positions` is a local presentational component
    whose `className` is omitted at both call sites, like its siblings in
    the same file.
  - `normalizeSection`'s `page` reads as required because it has no
    default, but `owliverConfig` deliberately calls it without one: `page`
    only builds a fallback `where` label, and that caller passes `where`
    explicitly, so the branch that would read it never runs. Stating the
    parameter object makes `page` optional, which is what the function has
    always accepted.

`npm run typecheck` is now 0 errors, from 71 when this migration started
and 20 when Phase 11 began. Nothing was suppressed to reach it: there is
no `@ts-ignore` or `@ts-expect-error` added anywhere in this branch.

4/4 byte-identical, suite and bundle unchanged.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HBG1wnuRfJKCstGB8Fekr8

src/components/ai-assistant/AssistantPanelContext.tsx

@@ -268,7 +268,7 @@ export function AssistantPanelProvider({ role, pathname, children }) {
 
   /* Width is written on every drag frame, so persistence is debounced rather
      than hitting sessionStorage sixty times a second. */
-  const setWidthState = React.useCallback((next) => {
+  const setWidthState: any = React.useCallback((next) => {
     const clamped = clampWidth(next);
     setWidth(clamped);
     clearTimeout(setWidthState.timer);