feat(client): atlas roads/settlements overlays + legend + server-API data delivery (T-960, T-949)

T-960: gen_l2_roads (MaintenanceAuthority-colored polylines, rail styling, junction markers) + gen_l3_settlements (size-scaled markers, capital shape, name labels) overlays — cities render on generated bodies for the first time; left-side generation legend panel (D-226 item 3, data-driven per-overlay spec, implant component library); protocol.gd decodes road_graph/settlements + the two new response types. T-949: system_index/atlas_app/overview_screen migrated off the direct star_map_data.json read to StarMapRequest over the bridge (loading state + replay-on-connect, no silent file fallback); atlas_viewer _load_markers requests CityNamesResponse for non-Sol bodies; Sol keeps the legacy authored markers.json geometry read (D-236/T-1073, load-bearing guard). Lead fix: _send_star_map_request now carries the same guard as request_star_map — the autoload's _star_map_wanted leaked across gdUnit suites and the unguarded replay-on-CONNECTED crashed 8 pre-existing flow tests on a Nil bridge; reset_test_state clears the flag. Fixtures regenerated via gen_fixtures (road/settlement samples). Full suite 2946/2946.

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

client/ui/implant/widgets/system_index.gd

@@ -1,31 +1,69 @@
 class_name SystemIndex
-## Shared system data loader for implant apps (#844).
-## Static helper — call as SystemIndex.get_sorted_systems().
+## Shared, cached system data loader for implant apps (#844, T-949).
+##
+## T-949: replaces the direct star_map_data.json FileAccess read with a
+## StarMapRequest over the bridge (D-010 — the client never reads game data
+## files directly). A static cache so every caller (AtlasApp's Reach screen,
+## the economics OverviewScreen) shares one fetch instead of each re-asking.
+##
+## Usage per caller:
+##   1. Call request_refresh() once (e.g. in _ready()/on_install()) — idempotent,
+##      no-op once loaded or already in flight.
+##   2. Connect to SimBridge.star_map_received and, in the handler, re-pull
+##      get_sorted_systems() to refresh with the now-populated list.
+## The Atlas can open before the bridge finishes its handshake —
+## SimBridge.request_star_map() remembers the request and fires it
+## automatically the instant the connection reaches CONNECTED, so callers
+## never need to poll or retry themselves.
 
-const DATA_PATH := "res://data/star_map_data.json"
+static var _cache: Array = []
+static var _loaded: bool = false
+static var _requested: bool = false
 
 
+## Sorted node list (by proper_name, falling back to system_id), or [] if the
+## star map has not arrived yet. Callers should re-pull this after
+## SimBridge.star_map_received fires.
 static func get_sorted_systems() -> Array:
-	if not FileAccess.file_exists(DATA_PATH):
-		push_warning("SystemIndex: %s not found" % DATA_PATH)
-		return []
-	var file := FileAccess.open(DATA_PATH, FileAccess.READ)
-	if file == null:
-		push_warning("SystemIndex: could not open %s" % DATA_PATH)
-		return []
-	var parsed: Variant = JSON.parse_string(file.get_as_text())
-	file.close()
-	if not (parsed is Dictionary):
-		return []
-	var nodes: Array = []
-	for node: Dictionary in parsed.get("nodes", []):
+	return _cache
+
+
+static func is_loaded() -> bool:
+	return _loaded
+
+
+## Ask the bridge for the star map if it hasn't been fetched yet. Safe to call
+## from every screen's _ready()/on_install() — idempotent once loaded or a
+## request is already in flight.
+static func request_refresh() -> void:
+	if _loaded or _requested:
+		return
+	_requested = true
+	SimBridge.request_star_map()
+
+
+## Feed a decoded StarMapResponse (from a SimBridge.star_map_received handler)
+## into the cache. Sorts once here so every caller gets the same order for free.
+## Only a "Ready" status is trusted — an Error response (protocol.gd's
+## star_map_response_from_raw already reduces it to status/error/nodes=[])
+## must NOT mark the cache _loaded, and must clear _requested so a later
+## request_refresh() retries instead of treating the failed fetch as
+## permanently done.
+static func ingest(response: Dictionary) -> void:
+	if str(response.get("status", "")) != "Ready":
+		_requested = false
+		return
+	var nodes: Array = response.get("nodes", [])
+	var sorted: Array = []
+	for node: Dictionary in nodes:
 		var sid: String = node.get("system_id", "")
 		if not sid.is_empty():
-			nodes.append(node)
-	nodes.sort_custom(
+			sorted.append(node)
+	sorted.sort_custom(
 		func(a: Dictionary, b: Dictionary) -> bool:
 			var na: String = a.get("proper_name", a.get("system_id", ""))
 			var nb: String = b.get("proper_name", b.get("system_id", ""))
 			return na < nb
 	)
-	return nodes
+	_cache = sorted
+	_loaded = true