Ok, I have a tall order in regards to FastAPI using SQLAlchemy with an SQLite database and Pydantic schemas for validation, but focus on the database design aspect, take a deep breath, really analysis and think step-by-step about my current configuration and the problem I am asking you to solve.

I have a database built up for Concepts, using a database model for a Concept, all it contains is an id as the primary key, and a name as a string, the Concepts can be grouped to other Concepts through a ConceptGroup table which contains two foreign keys pointing to Concept.id, the parent: group_concept_id and child: concept_id, this provides a many-to-many relationship.

So, the task at hand, for every Concept, I want the ability to dynamically store data into the database, what I need to be able to do is create a Concept, any grouping or relationships with other Concepts is irrelevant at this stage, linked to a Concept could be a custom table with specially defined fields(or columns if you prefer), since this table is to be created by the user, the FastAPI backend has no foreknowledge of the table.

So we need FastAPI endpoints for creating a table for a specific Concept, the ability to directly query this table, query a list of tables for a specific Concept, to add rows to the table, update rows, and delete rows, as well as updating the structure of the table, allow foreign key linking as a field within these tables, and even though the tables are directly linked to a Concept, I want to allow other Concepts, if needed, to access these tables, the Concept it is linked to is merely the "owner" of this type of data.

The structure of the table should be stored within the database as well, what fields are in the table, the fields data types(even custom ones that use a set type as a base, but I can provide custom functionality for).
The main example I have right now is Files, Fingerprints and Images.
Files:
File as a Concept entry, the idea is it is the concept of a File stored digitally on the computer somewhere, and only cares about local files.
It would contain a File data table linked to this Concept, containing simply a path to the file as a string.

Fingerprints:
This contains a hard SHA512 hash of a files data, so like before, Fingerprint is a Concept, and the Fingerprint data table contains the hash as a string, and it should index on this hash.

Images:
Image as a Concept entry, like File, except this refers specifically to the idea of an Image, rather then to specific files, so the Image data table will store an imagehash generated perceptual hash, using average_hash, and stored as a hex string, it can also store the format(jpeg/png/gif etc), width, height, bits per pixel, channels.

Now, the idea is we can link these data tables together, even though they belong to different Concepts:
- File just refers to a location on disk, a path as a string; for the contents of the file, we link it to the Fingerprint data table, all files will have a Fingerprint, but not all Fingerprints will have Files, as a File might move locations, or be deleted, but the idea of the hash remains, even if the file no longer exists.
- Fingerprint, I already spoke a lot about this, but this is almost an immutable data table, we add Fingerprints into it, but never remove them, but the link table linking Files to Fingerprints will constantly change as the files do.
- Image is similar to a Fingerprint, and is linked with File as well, however, in this case not all Files are Images, and not all Images are Files, as a file might get deleted from disk, but the Image data is more conceptual.

There is another Concept: Caption, what a Caption is, is text describing something, be it an image, a video, sound or even a book, for my purposes, a caption refers to something I will be using for training AI models, with Image-Caption pairs for example, but a Caption might have different sources, so for anything that can be Captioned, multiple captions might exist.
For the examples I gave above, a Caption might originate from a .txt file, so we might link File data table to the Caption data table, but only for Caption files.
Captions don't need to be Fingerprinted, so we never link them.
An Image is linked to a Caption usually via a Dataset, a Dataset defines groups of various types of data, the Dataset we will focus on is Image-Caption pairs, so it links the Image data to the Caption data, with each Image having it's own Captions, but a Caption would not be attached to multiple Images.

So, these were just use-case examples of how I would want to use the Concept data table system that I want you to design, do not worry about Files, Fingerprints, Images, Datasets or Captions, just focus on designing a database structure that allow me to later, through FastAPI endpoints(driven by a REACT frontend), to create, populate and manage these Concept data tables.

Let's think this through in a step-by-step way, take a breath and put all the pieces together to create a robust dynamic table system using SQLAlchemy for an SQLite database.