Rename Step Line to Gig Line

Update the game name in project.godot, export presets, UI/marquee/title strings, packaging (AppImage/NSIS/desktop/appdata), tools, docs, and the generated prop GLBs. Packaging assets and README screenshots are regenerated. Headless suite 209/209 and Python tooling tests pass.

packaging/linux/gig-line.appdata.xml

@@ -0,0 +1,23 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<component type="desktop-application">
+  <id>net.gigline.game</id>
+  <name>Gig Line</name>
+  <summary>Workplace security simulation on Hollywood Boulevard</summary>
+  <url type="homepage">https://git.allucanget.biz/zwitschi/security-game</url>
+  <developer id="net.gigline"><name>Gig Line Team</name></developer>
+  <description>
+    <p>
+      Gig Line is a workplace security simulation about observation, communication,
+      access verification, and proportionate escalation. Guard the steps and entrance
+      of venues around Hollywood Boulevard: direct tourists, verify wristbands and IDs,
+      screen guests, and escalate only when you have to.
+    </p>
+  </description>
+  <launchable type="desktop-id">gig-line.desktop</launchable>
+  <metadata_license>CC0-1.0</metadata_license>
+  <project_license>MIT</project_license>
+  <content_rating type="oars-1.1" />
+  <releases>
+    <release version="0.2.0" date="2026-10-31"/>
+  </releases>
+</component>