chore(ts): replace 7 \as unknown as\ shims with proper types

Most of the existing coercions are legitimate (Drizzle raw-SQL row
shapes, linkedom DOMParser interop, fit-file-parser's loose \`any\`
callback API) — leaving those is honest. The ones cleaned up here
were shims around APIs that have real types we just hadn't wired:

- **\`window.__leafletMap\`** (4 sites: MapHelpers.tsx, SessionView.tsx ×3)
  Added \`Window\` declaration in \`apps/planner/app/types/global.d.ts\`.
  Callers now use plain \`window.__leafletMap\` typed as
  \`L.Map | undefined\`.

- **\`L.markerClusterGroup\`** (PoiPanel.tsx) — leaflet.markercluster
  augments the global \`L\` namespace at runtime but ships no types.
  Added a \`declare module \"leaflet\"\` block in the same global.d.ts
  with a minimal signature for what we actually use.

- **\`L.DomEvent.preventDefault / .stop\`** taking a Leaflet event
  rather than a native one (PlannerMap.tsx, RouteInteraction.tsx,
  NoGoAreaLayer.tsx). Leaflet events carry the native event under
  \`.originalEvent\`; using that drops the cast entirely.

- **\`_creds as unknown as OAuthCredentials\`** orphan in
  wahoo/webhook.ts — \`_creds\` was unused inside the callback (the
  void-cast was a no-op preserving the type for documentation).
  Replaced with \`async ()\`, dropped the unused import.

Net: 26 \`as unknown as\` / \`as any\` sites → 19, all remaining ones
gated by external lib interop or Drizzle raw-SQL.

Full repo: pnpm typecheck / lint / test all green.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/journal/app/lib/connected-services/providers/wahoo/webhook.ts

@@ -9,7 +9,6 @@ import { fitToGpx } from "../../fit.ts";
 import { fetchWithTimeout } from "../../../http.server.ts";
 import { isAlreadyImported, importActivity } from "../../../sync/imports.server.ts";
 import { getServiceByProviderUser, withFreshCredentials } from "../../manager.ts";
-import type { OAuthCredentials } from "../../types.ts";
 import type { WebhookEvent, WebhookReceiver } from "../../registry.ts";
 
 interface WahooWebhookBody {
@@ -52,8 +51,7 @@ export const wahooWebhook: WebhookReceiver = {
       // through withFreshCredentials so the manager has a chance to refresh
       // a near-expired credential before any subsequent Wahoo call this
       // handler might make.
-      const buffer = await withFreshCredentials(service.id, async (_creds) => {
-        void (_creds as unknown as OAuthCredentials);
+      const buffer = await withFreshCredentials(service.id, async () => {
         const resp = await fetchWithTimeout(event.fileUrl!);
         if (!resp.ok) throw new Error(`Wahoo file download failed: ${resp.status}`);
         return Buffer.from(await resp.arrayBuffer());