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/activity-locations/proposal.md

@@ -0,0 +1,29 @@
+## Why
+
+Activities and routes display as bare stat rows — nothing tells a feed reader *where* "Sunday ride, 62 km" happened, which is often the most interesting fact. Endurain reverse-geocodes activity start points into city/country names (reviewed 2026-07-06), but does it by calling Nominatim/geocode.maps.co — a third-party request carrying user location that trails' privacy principles rule out. We can have the feature without the leak: an **offline** reverse geocoder using a bundled place dataset, running entirely on-instance.
+
+## What Changes
+
+- New shared package capability: offline reverse geocoding — nearest populated place (name, admin region, ISO country) for a coordinate, from a bundled GeoNames-derived dataset (`cities500`-class, a few MB), no network calls.
+- Activities and routes gain a derived **location label** ("Freiburg, Germany"), computed at save/import time from the geometry's start point and stored on the row.
+- Location shows on detail pages and feed/list cards; localized country names via the existing i18n locales.
+- **Privacy-coupled**: the label derives from where the track starts, so it is masked whenever the start location is hidden — it follows the same rules as the map/start data under the `activity-privacy-controls` change (if that lands, its `hideLocation`-style flag governs this label; until then, the label is only shown where the geometry itself is visible).
+- Backfill of existing rows via a one-shot background job.
+- Not in scope: full address geocoding, location search/filtering, per-point location, and any online geocoding fallback.
+
+## Capabilities
+
+### New Capabilities
+- `activity-locations`: Offline reverse geocoding of route/activity start points into display labels — dataset, derivation timing, storage, display, masking rule, and backfill.
+
+### Modified Capabilities
+
+<!-- none — feed/detail specs gain content additively; masking defers to activity-privacy-controls' capability when present -->
+
+## Impact
+
+- New `packages/geocode` (or module in an existing package): bundled dataset + nearest-place lookup (kd-tree/grid), pure and unit-tested; used by the journal only.
+- `packages/db`: `location_name`, `location_country` (text, nullable) on `activities` and `routes` + migration.
+- Journal: set at gpx-save/import time; one-shot pg-boss backfill job; feed card + detail page display (i18n).
+- Privacy manifest: note that location labels are derived on-instance with no third-party calls.
+- Bundle size: the dataset ships server-side only (journal), never to the browser.