Add northern pursuit scenario

docs/ROADMAP.md

@@ -3,6 +3,7 @@
 ## Milestone 0: Project Foundation
 
 - Godot 4 project opens and runs.
+- Godot 4.6 project metadata exists.
 - Main battle scene loads a JSON battle.
 - Rules and presentation are separated enough to keep iterating.
 
@@ -20,7 +21,7 @@
 - Destination victory conditions and objective map markers exist.
 - Turn-limit conditions and HUD turn-limit display exist.
 - Victory reward summary is visible.
-- Next-battle flow exists across the current seventeen-scenario campaign.
+- Next-battle flow exists across the current eighteen-scenario campaign.
 - Campaign completion and new-campaign reset exist.
 - Reward inventory can be brought into the next battle.
 
@@ -51,7 +52,7 @@
 - Party roster persistence has a first save-file skeleton.
 - Level, experience, and equipment persistence.
 - Chapter selection and save/load.
-- Linear seventeen-scenario campaign order exists.
+- Linear eighteen-scenario campaign order exists.
 - Save reset exists.
 - Victory rewards, consumable counts, equipment stock, and equipped gear persist.
 - A basic pre-battle shop with scenario-specific stock exists. Sell-back and richer item management are still planned.
@@ -76,6 +77,7 @@
 - Fifteenth-scenario content exists with Ye outer defense, Zhang He as a deployable officer, and 014 branch reactions.
 - Sixteenth-scenario content exists with Ye inner siege, Zhang He deployment, and 015 branch reactions.
 - Seventeenth-scenario content exists with Ye surrender, last loyalist resistance, and 016 branch reactions.
+- Eighteenth-scenario content exists with Northern Pursuit, Yuan Shang's rearguard, and 017 branch reactions.
 
 ## Milestone 5: Presentation