feat: add proximity query support

[nandor23]

This PR adds support for proximity queries. All queries use EF.Functions.Match() as the entry point, with proximity expressions composed via Pdb.Proximity(), Pdb.ProximityRegex(), and Pdb.ProximityArray() factories chained through .Within() and .WithinOrdered().

Basic proximity

context.Products.Where(p =>
    EF.Functions.Match(p.Description, Pdb.Proximity("sleek").Within(1, "shoes")));

SELECT id, name, description
FROM products
WHERE description @@@ (('sleek' ## 1) ## 'shoes');

Ordered proximity

context.Products.Where(p =>
    EF.Functions.Match(p.Description, Pdb.Proximity("sleek").WithinOrdered(1, "shoes")));

SELECT id, name, description
FROM products
WHERE description @@@ (('sleek' ##> 1) ##> 'shoes');

Proximity with regex

context.Products.Where(p =>
    EF.Functions.Match(p.Description, Pdb.ProximityRegex("sl.*").Within(1, "shoes")));

SELECT id, name, description
FROM products
WHERE description @@@ ((pdb.prox_regex('sl.*') ## 1) ## 'shoes');

With maxExpansions set to 100:

context.Products.Where(p =>
    EF.Functions.Match(p.Description, Pdb.ProximityRegex("sl.*", 100).Within(1, "shoes")));

SELECT id, name, description
FROM products
WHERE description @@@ ((pdb.prox_regex('sl.*', 100) ## 1) ## 'shoes');

Proximity with array

context.Products.Where(p =>
    EF.Functions.Match(p.Description, Pdb.ProximityArray("sleek", "white").Within(1, "shoes")));

SELECT id, name, description
FROM products
WHERE description @@@ ((pdb.prox_array('sleek', 'white') ## 1) ## 'shoes');

Arrays can mix tokens with regex or nested arrays.

context.Products.Where(p =>
    EF.Functions.Match(
        p.Description,
        Pdb.ProximityArray(Pdb.ProximityRegex("sl.*"), Pdb.ProximityArray("white"))
            .Within(1, "shoes")));

SELECT id, name, description
FROM products
WHERE description @@@ ((pdb.prox_array(pdb.prox_regex('sl.*'), pdb.prox_array('white')) ## 1) ## 'shoes');

Chained proximity

Multiple proximity clauses compose left to right.

context.Products.Where(p =>
    EF.Functions.Match(
        p.Description,
        Pdb.Proximity("sleek")
            .Within(1, "running")
            .Within(2, Pdb.ProximityArray("sneakers", Pdb.ProximityRegex("sho.*")))));

SELECT id, name, description
FROM products
WHERE description @@@ ((('sleek' ## 1) ## 'running') ## 2) ## pdb.prox_array('sneakers', pdb.prox_regex('sho.*'));

[philippemnoel]

Nice! I didn't look enough at the project yet to review this, but since it's still a WIP we can merge this and then pick up from that slate once ready. We're wrapping up the Drizzle ORM first, and this will be next.

If you want to see, we add all snippets to the official docs like here: https://github.com/paradedb/paradedb/tree/add-drizzle-snippets. We'll need to do this with the EFCore ORM