feat(ui): add system population and GDP to star map info panel (#785)

Star map popup now shows POPULATION and GDP rows when data is present.
Generation script updated to compute GDP from population × tier-based
per-capita schedule. 275/301 systems have GDP data (26 uninhabited
correctly omitted).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

client/ui/star_map.gd

@@ -507,10 +507,13 @@ func _rebuild_info_panel() -> void:
 
 	# Population + GDP
 	var population: String = node.get("population", "")
-	if not population.is_empty():
+	var gdp: String = node.get("gdp", "")
+	if not population.is_empty() or not gdp.is_empty():
 		_info_panel.add_component(ImplantDataRow.new(""))  # blank line spacer
-		_info_panel.add_component(ImplantDataRow.new("pop " + population))
-	_info_panel.add_component(ImplantDataRow.new("GDP —"))
+		if not population.is_empty():
+			_info_panel.add_component(ImplantDataRow.new("pop  " + population))
+		var gdp_label: String = "gdp  " + (gdp if not gdp.is_empty() else "—")
+		_info_panel.add_component(ImplantDataRow.new(gdp_label))
 
 	# ── GTTR excerpt ─────────────────────────────────────────────────────────
 	var gttr: String = node.get("gttr_excerpt", "")

tooling/generate-star-map-data.py

@@ -106,6 +106,45 @@ def parse_gttr_excerpt(system_id: str) -> str:
     return " ".join(paragraph_lines)
 
 
+GDP_PER_CAPITA: dict = {
+    5: 75_000,
+    4: 40_000,
+    3: 15_000,
+    2: 5_000,
+    1: 2_000,
+    0: 500,
+}
+
+
+def infer_tier_from_population(pop: int) -> int:
+    """Infer an economic tier from total population when no explicit tier is set."""
+    if pop >= 5_000_000_000:
+        return 5
+    if pop >= 1_000_000_000:
+        return 4
+    if pop >= 200_000_000:
+        return 3
+    if pop >= 10_000_000:
+        return 2
+    return 1
+
+
+def compute_gdp(total_pop: int, economic_tier: int | None) -> str:
+    """Return a formatted GDP string in Tractus, or empty string if no population."""
+    if total_pop == 0:
+        return ""
+    tier = economic_tier if economic_tier is not None else infer_tier_from_population(total_pop)
+    per_cap = GDP_PER_CAPITA.get(tier, GDP_PER_CAPITA[1])
+    value = total_pop * per_cap
+    if value < 1_000_000_000:
+        return f"{value / 1_000_000:.1f} MTr"
+    if value < 1_000_000_000_000:
+        return f"{value / 1_000_000_000:.1f} BTr"
+    if value < 1_000_000_000_000_000:
+        return f"{value / 1_000_000_000_000:.1f} TTr"
+    return f"{value / 1_000_000_000_000_000:.1f} QTr"
+
+
 def build_adjacency(edges: list) -> dict:
     """Build a map from system_id to list of adjacent system_ids from edges."""
     adj: dict = {}
@@ -162,6 +201,10 @@ def generate() -> dict:
         GROUP BY system_id
     """)
     station_stats = {row["system_id"]: dict(row) for row in cur.fetchall()}
+
+    # Economic tier for GDP calculation
+    cur.execute("SELECT system_id, economic_tier FROM system_economy")
+    econ_tiers = {row["system_id"]: row["economic_tier"] for row in cur.fetchall()}
     conn.close()
 
     adjacency = build_adjacency(star_map["edges"])
@@ -204,6 +247,9 @@ def generate() -> dict:
 
         entry["bodies"] = "%d habitable · %d inhabited" % (hab, inh)
         entry["population"] = "{:,}".format(total_pop)
+        gdp_str = compute_gdp(total_pop, econ_tiers.get(sid))
+        if gdp_str:
+            entry["gdp"] = gdp_str
         if gttr:
             entry["gttr_excerpt"] = gttr
         if n.get("is_gateway"):