docs+openspec: prior-art research (Organic Maps, Endurain, wanderer) and 15 proposals

Add docs/inspirations.md as the durable record of the 2026-07-05/06
prior-art research — per-project learnings with source paths, canonical
credit lines, and the changes each spawned — and extend the
acknowledgment lists in philosophy.md/architecture.md (Organic Maps,
Endurain, wanderer).

New OpenSpec changes (proposal/design/specs/tasks each):
- Organic Maps: elevation-profile-hardening, gpx-parser-robustness,
  hiking-time-estimate, poi-index, hiking-foot-profile
- Endurain: account-export, activity-duplicate-review,
  fit-parsing-hardening, activity-locations, self-hosting-guide,
  activity-privacy-controls
- wanderer: federation-hardening, link-share-tokens
- credits-page (user-visible acknowledgments)

Updated in-flight changes with wanderer prior-art sections:
route-federation, route-discovery.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

openspec/changes/hiking-time-estimate/tasks.md

@@ -0,0 +1,23 @@
+## 1. Model function
+
+- [ ] 1.1 Create `packages/gpx/src/hiking-time.ts`: `toblerSpeedKmh(slope)`, `hikingTimeSeconds(points)`, `cumulativeHikingTimeSeconds(points)` — haversine horizontal distance, elevation slope with ±100% clamp, flat-speed fallback for missing elevation
+- [ ] 1.2 `hiking-time.test.ts`: flat 5 km ≈ 1 h; −5% slope is the fastest; ±20% asymmetry (uphill > downhill > flat); missing-elevation fallback; clamp prevents near-zero speeds; cumulative array matches total
+- [ ] 1.3 Export from `packages/gpx/src/index.ts`
+
+## 2. Per-day support
+
+- [ ] 2.1 Extend `computeDays(waypoints, tracks, opts?)` with `opts.estimateHikingTime` populating optional `DayStage.estimatedTimeSec` from the cumulative time array between stage boundaries
+- [ ] 2.2 Tests: day times sum to route total; without opt-in the output is deep-equal to before; single-day route gets one stage with the full estimate
+
+## 3. Planner integration
+
+- [ ] 3.1 In `use-routing.ts`, when the active profile is the foot profile (`hiking` if the `hiking-foot-profile` change has landed, otherwise `trekking`), compute `estimatedTimeSec` from `enriched.coordinates` and include it in the route stats written for the sidebar
+- [ ] 3.2 Display in `WaypointSidebar.tsx`: add the time to the compact stat line and the stats grid when present, with "≈" and h/min formatting
+- [ ] 3.3 Display per-day times in `DayBreakdown.tsx` (pass the opt-in flag to the planner's `computeDays` call when the foot profile is active)
+- [ ] 3.4 Add i18n strings (en: "Est. walking time" etc., de: "Gehzeit ca.") to `packages/i18n` planner namespaces — no hardcoded strings
+
+## 4. Verification
+
+- [ ] 4.1 Extend the planner e2e suite: with the Hiking profile a computed route shows a walking-time stat; switching to a cycling profile hides it
+- [ ] 4.2 Manual sanity check against a known hike (e.g. a local route with signposted time) — estimate should be in the right ballpark
+- [ ] 4.3 Run `pnpm typecheck && pnpm lint && pnpm test && pnpm test:e2e`