Deepen three architectural seams: FIT consolidation, host election extraction, injectable db

- Extract shared fitToGpx into connected-services/fit.ts (FIT is a Garmin
  open standard used by Wahoo, Coros, Garmin — not provider-specific)
- Add importActivity() to sync/imports.server.ts so providers call one
  function instead of createActivity + recordImport separately; eliminates
  direct dependency on activities.server.ts from provider adapters
- Update wahoo importer + webhook to use both shared helpers
- Extract useHostElection(yjs) hook from useRouting so host election is
  independently testable without mounting the full routing stack
- Add setDb() to journal db.ts for module-level injection in unit tests

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/planner/app/lib/use-host-election.ts

@@ -0,0 +1,28 @@
+import { useEffect, useState } from "react";
+import { electHost } from "./host-election.ts";
+import type { YjsState } from "./use-yjs.ts";
+
+export function useHostElection(yjs: YjsState | null): boolean {
+  const [isHost, setIsHost] = useState(false);
+
+  useEffect(() => {
+    if (!yjs) return;
+
+    const checkHost = () => {
+      const states = yjs.awareness.getStates() as Map<number, Record<string, unknown>>;
+      const localId = yjs.awareness.clientID;
+      const { isHost: amHost, role } = electHost(states, localId);
+      setIsHost(amHost);
+      yjs.awareness.setLocalStateField("role", role);
+    };
+
+    yjs.awareness.on("change", checkHost);
+    checkHost();
+
+    return () => {
+      yjs.awareness.off("change", checkHost);
+    };
+  }, [yjs]);
+
+  return isHost;
+}

apps/planner/app/lib/use-routing.ts

@@ -1,7 +1,7 @@
 import { useCallback, useEffect, useRef, useState } from "react";
 import * as Y from "yjs";
 import type { YjsState } from "./use-yjs.ts";
-import { electHost } from "./host-election.ts";
+import { useHostElection } from "./use-host-election.ts";
 import {
   hashNoGoAreas,
   mergeGeoJsonSegments,
@@ -51,7 +51,7 @@ function restoreWaypoints(yjs: YjsState, snapshot: WaypointData[], restoringRef:
 export type RouteError = "no_route" | "failed" | "rate_limit" | null;
 
 export function useRouting(yjs: YjsState | null, sessionId: string) {
-  const [isHost, setIsHost] = useState(false);
+  const isHost = useHostElection(yjs);
   const [computing, setComputing] = useState(false);
   const [routeError, setRouteError] = useState<RouteError>(null);
   const [routeStats, setRouteStats] = useState<RouteStats>({});
@@ -67,26 +67,6 @@ export function useRouting(yjs: YjsState | null, sessionId: string) {
   // instead of N-1 on every recompute.
   const segmentCacheRef = useRef<SegmentCache>(new SegmentCache());
 
-  // Host election via Yjs awareness
-  useEffect(() => {
-    if (!yjs) return;
-
-    const checkHost = () => {
-      const states = yjs.awareness.getStates() as Map<number, Record<string, unknown>>;
-      const localId = yjs.awareness.clientID;
-      const { isHost: amHost, role } = electHost(states, localId);
-      setIsHost(amHost);
-      yjs.awareness.setLocalStateField("role", role);
-    };
-
-    yjs.awareness.on("change", checkHost);
-    checkHost();
-
-    return () => {
-      yjs.awareness.off("change", checkHost);
-    };
-  }, [yjs]);
-
   const computeRoute = useCallback(
     async (waypoints: WaypointData[]) => {
       if (!yjs || !isHost || waypoints.length < 2) return;