Fix for objects.inv (#1552)

This PR tweaks the `qml` build tool such that the generated objects.inv
files match the naming and uris for the demos on pennylane.ai. This PR
should fix #1550.

Note: This has been tested locally. ~We should verify it works when
building all demos as wel.~ Tested for all demos successfully
[here](https://github.com/PennyLaneAI/qml/actions/runs/17866805882)

---------

Co-authored-by: Alan Martin <[email protected]>

Author: doctorperceptron

lib/qml/lib/demo.py

@@ -226,7 +226,7 @@ def build(
         for demo in demos:
             logger.info("Loading objects.inv for '%s'", demo.name)
             demo_inv = soi.Inventory(
-                ctx.repo_root / "demos" / demo.name / "objects.inv"
+                ctx.build_dir / f"{demo.name}_objects.inv"
             )
 
             # Only add entries that don't already exist in the merged inventory file
@@ -274,7 +274,7 @@ def _build_demo(
     quiet: bool,
     dev: bool,
 ):
-    out_dir = ctx.repo_root / "demos" / demo.name
+    out_dir = ctx.repo_root / "demos"
     fs.clean_dir(out_dir)
 
     generate_requirements(ctx, demo, dev, out_dir / "requirements.txt")
@@ -333,7 +333,7 @@ def _build_demo(
 
     # Move the objects.inv file so we can merge them once all the demos are built
     if target is BuildTarget.HTML:
-        fs.copy_any(ctx.build_dir / "html/objects.inv", out_dir)
+        fs.copy_any(ctx.build_dir / "html/objects.inv", ctx.build_dir / f"{demo.name}_objects.inv")
 
 
 def _package_demo(
@@ -357,7 +357,7 @@ def _package_demo(
     fs.clean_dir(dest)
 
     with open(
-        (sphinx_output / "demos" / demo.name / demo.name).with_suffix(".fjson"), "r"
+        (sphinx_output / "demos" / demo.name).with_suffix(".fjson"), "r"
     ) as f:
         html_body = json.load(f)["body"]