feat(engine): T-1131 browse data proxy — six entity kinds, index+detail, one wire envelope (D-254 SS4)

browse_reader.rs: BrowseReader on the CityContextReader::open() pattern
— six index + six detail reads against systems.db (bodies filterable by
containing system; system/corporation/commodity details fold their join
partners). browse_proxy.rs: BrowseRequest{browse, kind, query} /
BrowseResponse{kind, status, index, detail} wire types + dispatcher;
BrowseIndexRow{id, primary, secondary} generic across kinds;
BrowseDetail a per-kind enum of field-exhaustive structs.

Demux: Inbound::BrowseRequest is the FIFTH map shape — deliberately the
last; the doc's four-shape ceiling is re-pinned at five with rationale
(six kinds x two forms folded into ONE envelope whose internal enums
pick sub-behavior, the AtlasLayerRequest.up_to precedent, instead of
twelve top-level shapes) and a hard rule that a sixth shape must
migrate to the D-225 tagged-envelope framing. Served for BOTH roles,
connection-tagged 1:1 in-order like atlas/starmap/citynames.
serve_browse_requests pub so integration tests drive the true
end-to-end pipeline. Wire-only per D-254 (T-949 precedent); v1
exclusions (cascade geometry, event logs) respected.

30 unit tests + 7 bridge_tcp integration tests (six-kind round-trip
over real TCP, reader-can-browse, no crossed responses between two
readers, unknown-id NotFound, empty-table Ready); 2 pre-existing tests
updated for the new receive_bridge_inputs parameter.

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

server/src/main.rs

@@ -253,6 +253,25 @@ fn main() {
         ),
     }
 
+    // Data browser reader (D-254 §4, T-1131): read-only access to the six v1
+    // registry-tier entity kinds (star systems, bodies, stations,
+    // corporations, commodities, trait templates) for the companion app's
+    // browse UI. Absent -> BrowseRequests are answered with an Error status
+    // per request rather than a hard failure (matches every other reader's
+    // "unavailable, log + degrade" convention below).
+    match settled_reach_server::atlas::browse_reader::BrowseReader::open(&systems_db_path) {
+        Ok(reader) => {
+            tracing::info!("Browse reader opened: {:?}", systems_db_path);
+            app.insert_resource(
+                settled_reach_server::atlas::browse_reader::BrowseReaderResource(reader),
+            );
+        }
+        Err(e) => tracing::warn!(
+            "Browse reader unavailable ({}). Browse requests will error.",
+            e
+        ),
+    }
+
     // Body physical params reader for DistrictProfile carrier layer (T-1032, D-239 §1, D-240):
     // reads hydrosphere / atmosphere / planet_class on a cache miss so the Rayon
     // cascade work item stays DB-free (D-225 pattern).