feat: add a new API capability that returns the details of a single file

[Rakanhf]

Currently we have the GET /files/<project_id>/ endpoint, that returns the full list metadata of project files, but we do not have a mechanism to get the metadata of a single file. Sometimes we need the metadata of a single file instead of everything.

So a new endpoint is introduced GET /files/metadata/project_id/filename/

Example response :

{
    "name": "example.qgs",
    "size": 70989,
    "uploaded_at": "2025-12-11T12:45:13.814867+01:00",
    "is_attachment": false,
    "md5sum": "b6073c9090ade803b27ebea246d05dc0",
    "last_modified": "11.12.2025 11:46:37 UTC",
    "sha256": "b90038f2c92e4f467ffc35d2340fe8474cb37fc59df101014080701c8706796d",
    "versions": [
        {
            "version_id": "889e2e7b-b737-45a5-bd86-305bf47c1480",
            "md5sum": "b6073c9090ade803b27ebea246d05dc0",
            "size": 70989,
            "uploaded_at": "2025-12-11T12:46:37.777819+01:00",
            "display": "v20251211114637",
            "is_latest": true,
            "last_modified": "11.12.2025 11:46:37 UTC",
            "sha256": "b90038f2c92e4f467ffc35d2340fe8474cb37fc59df101014080701c8706796d"
        },
        {
            "version_id": "b798c092-2940-45ef-bf76-e5df3863fc56",
            "md5sum": "33a9af5beeb27bea3ff501dd337f814c",
            "size": 52536,
            "uploaded_at": "2025-12-11T12:46:14.627636+01:00",
            "display": "v20251211114614",
            "is_latest": false,
            "last_modified": "11.12.2025 11:46:14 UTC",
            "sha256": "c877d23aad89c92c7ad2fda11f056f82c6b866c4546857a68458db37046a045c"
        },
        {
            "version_id": "a3850bbd-450e-40df-8aec-a8cb070feb66",
            "md5sum": "baf0391def3de3f99d6af65b4df295f1",
            "size": 28596,
            "uploaded_at": "2025-12-11T12:45:13.814867+01:00",
            "display": "v20251211114513",
            "is_latest": false,
            "last_modified": "11.12.2025 11:45:13 UTC",
            "sha256": "2c3aefce237b6443c49289d8f61cb5f4d4f20f3bec44b3fd679b617be4a33ccd"
        }
    ]
}

[duke-nyuki]

Task linked: QF-6821 Add a new API capability that returns the details of a single file

[suricactus]

Thank you for the nice PR!

Small things to address, feel free to merge afterwards.