feat(todo): the server finds places through the instance's Photon (ADR 0033, D32)

Todo's locations search through the person's own instance, as Train's
planner does, not a public service: `SearchEndpoint` on `PlaceSearch`, for
those signed in, 60 searches a minute, nothing kept or logged. Its `Place`
carries the address's parts and the object in OpenStreetMap, and a shop's
car park or charger is left out, which came first for `Lindau EDEKA`.

`compose.todo-search.yaml` puts Todo's server on compose.search.yaml's
Photon. A file of its own: without it Todo starts as it did, and offers no
search.

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

deploy/compose.todo-search.yaml

@@ -0,0 +1,16 @@
+# Place search for Halkyon Todo (ADR 0033, D32): Todo's server on the Photon of
+# compose.search.yaml, which Train's server asks too. After both in .env:
+#
+#   COMPOSE_FILE=…:compose.todo.yaml:compose.search.yaml:compose.todo-search.yaml
+#
+# A file of its own: Todo starts without it, its app offering no search, and an instance
+# may run Photon for Train without Todo. Only Todo's server asks, for people signed in,
+# and neither what is searched nor what is found is kept or logged; a task's location is
+# sealed on the person's devices. Setting it up: sidecars/README.md, Todo.
+
+services:
+  todo-server:
+    environment:
+      PHOTON_URL: http://photon:2322/
+    networks:
+      - search