feat(simulation): T-1151 window par_iter + T-1150 granularity carrier (five touch points + aliasing tests)

T-1151: build_district_window_layer dispatches one Rayon task per row
(pure derive_window_cell via derive_at_metres), scattered row-major into
the flat arrays; a cfg(test) serial path backs the bit-identical
parallel-vs-serial golden.

T-1150: serde-default window_granularity (1=district, 4=quarter) +
window_min_wl_m on AtlasLayerRequest — additive, no sixth demux shape,
old frames decode unchanged (tested). Quarter mode = full
reclassification at 512m spacing over the same world rect ((4n)x(4n)
cells); WIRE_CAP_CELLS=4096 enforces n*granularity <= cap (quarter
clamps n to 16, the design doc's worked example). Granularity + min_wl
key ALL five touch points: DistrictWindowLayer echo, server FIFO-256
cache key (now a 5-tuple), per-connection coalescing key, client
request codec (omitted-at-default wire fields), client LRU key.

Mandatory aliasing regressions on both ends: identical (body, center, n)
at granularity 1 vs 4 produce distinct cache entries and correct
per-granularity payload shapes (server, 3-thread queue to avoid the
AnalyzeBody thread contention found while writing it) and distinct
client cache keys (gdUnit). Replay fixture regenerated — the layer
struct grew two echoed fields (231->254 bytes, content verified).

Client requests stay district-granularity by default — quarter requests
arrive with T-1153's rung selection.

client/scripts/protocol/atlas_map_protocol.gd

@@ -31,18 +31,32 @@ class_name AtlasMapProtocol
 ## [1, DISTRICT_WINDOW_MAX_N] itself and never trusts the wire value; the
 ## client-side default/cap constants (DISTRICT_WINDOW_DEFAULT_N/MAX_N) live on
 ## the regional-window viewer, not duplicated into the codec.
+##
+## `window_granularity`/`window_min_wl_m` (T-1150): the derivation-granularity
+## axis (district=1/omitted vs. quarter=4) and the octave cutoff, in whole
+## metres. Both OMITTED (not sent as 0) when at their default — this is
+## struct/key plumbing only (T-1150 scope): no caller in this codebase
+## requests quarter granularity yet (that's T-1153); this function just makes
+## it possible to ask, byte-compatible with every existing caller that
+## doesn't pass them.
 static func encode_atlas_layer_request(
 	mp,
 	body_id: String,
 	up_to: String = "Topography",
 	window_center: Variant = null,
-	window_n: int = 0
+	window_n: int = 0,
+	window_granularity: int = 0,
+	window_min_wl_m: int = 0
 ) -> PackedByteArray:
 	var msg := {"body_id": body_id, "up_to": up_to}
 	if window_center != null:
 		var center: Vector2i = window_center
 		msg["window_center"] = [center.x, center.y]
 		msg["window_n"] = window_n
+		if window_granularity != 0:
+			msg["window_granularity"] = window_granularity
+		if window_min_wl_m != 0:
+			msg["window_min_wl_m"] = window_min_wl_m
 	var result = mp.encode(msg)
 	if result.status != null:
 		push_error("Protocol: encode_atlas_layer_request failed: %s" % result.status)

client/scripts/protocol/protocol.gd

@@ -780,14 +780,19 @@ static func encode_request_bookmark_catalog() -> PackedByteArray:
 ## windowed district-resolution regional-map query — see
 ## atlas_map_protocol.gd's encode_atlas_layer_request doc for the wire shape.
 ## Omitted callers (every whole-body-layer call site predating T-1138) are
-## byte-unchanged.
+## byte-unchanged. window_granularity/window_min_wl_m (T-1150): same
+## byte-compatibility contract, see atlas_map_protocol.gd.
 static func encode_atlas_layer_request(
 	body_id: String,
 	up_to: String = "Topography",
 	window_center: Variant = null,
-	window_n: int = 0
+	window_n: int = 0,
+	window_granularity: int = 0,
+	window_min_wl_m: int = 0
 ) -> PackedByteArray:
-	return _amp().encode_atlas_layer_request(_mp(), body_id, up_to, window_center, window_n)
+	return _amp().encode_atlas_layer_request(
+		_mp(), body_id, up_to, window_center, window_n, window_granularity, window_min_wl_m
+	)
 
 
 ## Decode an AtlasLayerResponse (#969, D-225). Returns a Dictionary