feat(train): routes kept as sealed rows, planned on the map (ADR 0030, D44)

Routes are synced `route` rows (the model `SavedRoute`, as Flutter has a
`Route`), sealed as plans are; the migration `routes` only creates the
table, its space index and its cascade to the sync engine's spaces. A
route's payload holds its name, activity, profile, waypoints and the way
planned, points and elevations delta-coded and gzipped.

Home gets a fourth tab, Routes, and the planner: waypoints tapped on the
map, held and dragged, the last undone, a new route's first where the
phone is (GPS through the recorder's channel), the way planned by the
instance's BRouter after each change, an earlier answer dropped; its
distance, climb, descent, elevation and surfaces under the map.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

docs/adr/0030-halkyon-train.md

@@ -867,6 +867,23 @@ Strava. What was found, 27 Oct:
   descent, an elevation profile under the map and the surfaces it runs on as BRouter
   tells them (over distance and climb alone, and over loops of a given length, which
   BRouter can't make and Train would only guess at).
+  Built: the `routing` endpoint and the deploy (9a, `ab128550`, `7fcb91c6`); routes
+  as synced, sealed `route` rows and the planner (9b). A route's payload holds its
+  name, activity, profile, waypoints and the way planned (points to a micro-degree
+  and elevations to a decimetre, each delta-coded, its turns, its stretches),
+  gzipped as a workout's series are, since a planned route has thousands of points.
+  The server's model is `SavedRoute` on the table `route`, since Flutter's widgets
+  have a `Route` of their own. Home's fourth tab lists the routes; the planner is the
+  map above and the route's figures under it: a tap adds a waypoint, one held and
+  dragged moves it (held first, so that dragging the map never moves one), the
+  button above the map takes the last off, and the instance plans the way after each
+  change, an answer to an earlier change dropped once a later one is asked. A new
+  route starts where the phone is: the recorder's channel asks GPS for its last fix
+  of the past two minutes or a new one (15 s at most), the location permission asked
+  first (no package, as recording takes no other); on a device that can't tell it
+  starts empty. Surfaces are grouped from OpenStreetMap's tags as paved, compacted,
+  gravel, natural ground and not known. An instance without BRouter says so on the
+  planner.
 - **D45 Following a route** (recommended, the developer's; 28 Oct): the recording
   screen keeps its figures first and swipes to a map with the route, the track so far
   and the position, north or heading up as tapped, with a route or without (over the