fix(templates): fill pptx via direct zip/XML editing instead of PhpPresentation

Round-tripping real-world .pptx files through PhpPresentation's object model
was silently corrupting/losing content it doesn't fully model (themes, masters,
layouts, fonts), so placeholder replacement wasn't reliable. Now the service
edits the .pptx as a zip archive directly: only the touched slide XML text runs
and swapped image bytes change, everything else stays byte-identical to the
source file. Drops the now-unused phpoffice/phppresentation dependency.

composer.json

@@ -14,8 +14,7 @@
         "filament/filament": "^4.0",
         "laravel/framework": "^13.8",
         "laravel/sanctum": "^4.3",
-        "laravel/tinker": "^3.0",
-        "phpoffice/phppresentation": "^1.2"
+        "laravel/tinker": "^3.0"
     },
     "require-dev": {
         "fakerphp/faker": "^1.23",