Feature: Add Token-Based Dynamic Filtering and Hybrid Specifications Support

## Summary

Add support for parsing dynamic filters, sorting, and pagination from query parameters or JSON (token-based syntax) and integrating them with existing Specification Pattern implementations.

This feature would allow combining **dynamic filtering** (user-provided queries) with **business rules** (static specifications) in a hybrid approach, providing flexibility similar to GraphQL but within the familiar Specification framework.

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## Motivation

- Currently, specifications are defined statically in code. Dynamic scenarios (e.g., filtering from query strings in REST APIs) require custom code outside the library.
- Many APIs need **runtime filters** combined with **predefined business rules** (e.g., soft-delete, multi-tenancy).
- Adding token-based parsing (e.g., `Name~contains~foo;Priority~eq~high`) would:
- Reduce boilerplate code for parsing query strings.
- Enable hybrid use: static specs + dynamic filters together.
- Provide a consistent, extensible pattern for advanced querying.

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## Proposed Design

1. **TokenQuery Model**
Encapsulates filters, sorting, pagination, and selected fields parsed from query strings or JSON.

2. **TokenQueryParser**
Converts query strings or JSON into `TokenQuery` objects.

3. **Extensions for Specifications**
- `spec.ApplyTokenQuery(tokenQuery)`
- Merges dynamic filters with existing static specs.

4. **Supported Operations**
- Filtering: eq, neq, contains, startswith, endswith, gt, lt, between
- Sorting: `field:asc`, `field:desc`
- Pagination: page + pageSize
- Field selection (optional)

5. **Hybrid Support**
Specifications define static rules (e.g., `ActiveTodosSpec`)
TokenQuery applies additional runtime filters.

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## Example

```csharp
var tokenQuery = TokenQueryParser.FromQueryString("?filter=Name~contains~work;IsComplete~eq~true&sort=Priority:asc&page=1&pageSize=10");

var spec = new ActiveTodosSpec()
.ApplyTokenQuery(tokenQuery);

var result = await repository.ListAsync(spec);

No files or tests are named. Start by reading the existing Specification Pattern and repository APIs, then map the proposed TokenQuery model, TokenQueryParser, and ApplyTokenQuery extension onto them. Done means query-string or JSON filters, sorting, pagination, and hybrid static-plus-dynamic specifications support the listed operations.

Written by the indexing model from the issue text.