chore: rename Stirling-Image to ashim across entire codebase

Complete rebrand from Stirling-Image to ashim following the project
move to https://github.com/ashim-hq/ashim.

Changes across 117 files:
- Package scope: @stirling-image/* → @ashim/*
- GitHub URLs: stirling-image/stirling-image → ashim-hq/ashim
- Docker Hub: stirlingimage/stirling-image → ashimhq/ashim
- GitHub Pages: stirling-image.github.io → ashim-hq.github.io
- All branding text: "Stirling Image" → "ashim"
- Docker service/volumes/user: stirling → ashim
- Database: stirling.db → ashim.db
- localStorage keys: stirling-token → ashim-token
- Environment variables: STIRLING_GPU → ASHIM_GPU
- Python cache dirs: .cache/stirling-image → .cache/ashim
- SVG filter IDs, test prefixes, and all other references

apps/web/src/components/common/dropzone.tsx

@@ -69,7 +69,7 @@ export function Dropzone({ onFiles, accept, multiple = true, currentFiles = [] }
     >
       <div className="flex flex-col items-center gap-4 p-8">
         <div className="text-3xl font-bold text-muted-foreground/30">
-          Stirling <span className="text-primary/30">Image</span>
+          <span className="text-primary/30">ashim</span>
         </div>
         <button
           type="button"