Bump source to 0.9.2 and renumber the 0.x roadmap

- Set project.godot to 0.9.2 and add the matching changelog entry.
- Renumber the postponed work to 0.9.3 UI, 0.9.4 NPC, 0.9.5 textures and 0.9.6 integration, with 0.10.0 as the next minor release candidate.
- Remove the 1.0.0 milestone and post-1.0 planning; plan only 0.x patch/minor increments.
- Synchronize README, PLAN, architecture, status, memory and UI-copy version references.

CHANGELOG.md

@@ -4,7 +4,7 @@ All notable user-facing changes to Gig Line. The format follows
 [Keep a Changelog](https://keepachangelog.com/en/1.1.0/), and versions use
 Semantic Versioning.
 
-## [Unreleased]
+## [0.9.2] — 2026-11-02
 
 ### Added