docs: fix stale image-gen refs, Node prereq, version sync; drop dead icons.svg

- README: image gen is sd-server (cross-platform), not macOS/Ollama;
  Node 23.6+ note for self-checks; prefs store row in the data table.
- plan.md: superseded banners on the Ollama image-gen sections.
- gitea-release.sh: syncs Cargo.toml too; bumped to 0.1.3 to match.
- public/icons.svg: unreferenced — favicon.svg is the icon.

src-tauri/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "dm-pal"
-version = "0.1.0"
+version = "0.1.3"
 description = "AI-Powered Dungeon Master Toolkit"
 authors = ["DM-Pal Team"]
 license = ""