fix(client): post-sprint polish — protocol v21, schedule workaround, UI fixes

- Bump client protocol version 20 → 21 to match server (#822)
- Fix render_priority parameter name (was _render_priority, unused prefix)
- Fix debug console type inference (var sub := → var sub: String =)
- Economics panel: add population row, improve key hint text
- Stance indicator: hide on gameplay_occluded (D-170 fullscreen apps)
- Remove 5 broken clothing items from manifest and delete their GLBs
  (boots_work, coveralls_basic, jacket_utility, pants_cargo, shirt_henley)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

client/ui/debug_console.gd

@@ -248,7 +248,7 @@ func _dispatch_econ(parts: Array) -> void:
 			ERROR_COLOR,
 		)
 		return
-	var sub := parts[1].to_lower()
+	var sub: String = parts[1].to_lower()
 	match sub:
 		"inject":
 			_econ_inject(parts)

client/ui/implant/economics_panel.gd

@@ -218,7 +218,9 @@ func _rebuild_panel() -> void:
 
 	_panel.add_component(ImplantSeparator.new())
 
-	# ── GDP strip ─────────────────────────────────────────────────────────────
+	# ── Population + GDP strip ────────────────────────────────────────────────
+	var pop_str: String = node.get("population", "—")
+	_panel.add_component(ImplantDataRow.new("pop  " + pop_str))
 	var gdp_str: String = node.get("gdp", "—")
 	_gdp_row = ImplantDataRow.new("gdp  " + gdp_str)
 	_panel.add_component(_gdp_row)
@@ -257,7 +259,7 @@ func _rebuild_panel() -> void:
 	_panel.add_component(_placeholder_notice)
 
 	_panel.add_component(ImplantSeparator.new())
-	_panel.add_component(ImplantTextBlock.new("[ ] select system · N close"))
+	_panel.add_component(ImplantTextBlock.new("[  prev system  ]  next system  ·  N  close"))
 
 
 func _current_node() -> Dictionary:

client/ui/stance_indicator.gd

@@ -74,6 +74,13 @@ func _ready() -> void:
 	_panel.add_component(hbox)
 	_apply_stance("Walk")
 
+	# D-170: hide when fullscreen implant apps occlude gameplay
+	HudGroups.gameplay_occluded.connect(_on_gameplay_occluded)
+
+
+func _on_gameplay_occluded(occluded: bool) -> void:
+	visible = not occluded
+
 
 func _apply_stance(stance: String) -> void:
 	_current_stance = stance