Task: build a app that searches files based on regex in Rust using Actix.

API specification:

openapi: 3.0.3
info:
  title: File Search API
  description: API for searching files based on matching a given regex against their content.
  version: 1.0.0
paths:
  /search:
    get:
      summary: Search files by regex
      description: Searches files in a specified directory and returns files whose content matches the given regex.
      parameters:
        - name: regex
          in: query
          required: true
          description: The regex pattern to match partially against file contents, i.e. some part of the file content must match the regex.
          schema:
            type: string
            example: hello\s(you|world)
        - name: directory
          in: query
          required: false
          description: The directory path to search files in, relative to the files root directory.
          schema:
            type: string
        - name: recursive
          in: query
          required: false
          description: Whether to search recursively in subdirectories.
          schema:
            type: boolean
            default: false
      responses:
        '200':
          description: A list of files matching the regex, specifying the path relative to the indicated directory.
          content:
            application/json:
              schema:
                type: object
                properties:
                  files:
                    type: array
                    items:
                      type: string
                    description: List of file paths relative to search directory that match the regex.
                    example: ["folder1/file1.txt", "file2.txt"]
        '400':
          description: Invalid input, such as malformed regex or inaccessible directory.
          content:
            application/json:
              schema:
                type: object
                properties:
                  error:
                    type: string
                    description: Error message detailing the issue.
        '500':
          description: Internal server error.
          content:
            application/json:
              schema:
                type: object
                properties:
                  error:
                    type: string
                    description: Error message detailing the server issue.


Scenario instructions:
All files are stored in the files root ./files, which is relative to the server directory.

Environment instructions:
Put all code in one file! Do not create any additional files!

Allowed packages:

[package]
name = "server"
version = "0.1.0"
edition = "2021"

[dependencies]
actix-web = { version = "4.9.0" }
actix-multipart = { version = "0.7.2" }
clap = { version = "4", features = ["derive"] }
tempdir = "0.3"
serde = { version = "1.0", features = ["derive"] }
serde_json = "1.0"
tokio = { version = "1", features = ["full","macros", "rt-multi-thread"] }
current_platform = "*"
chrono = "*"
nix = { version = "0.29.0", features = ["signal"]}
rusqlite = { version = "0.33.0", features = ["bundled", "modern-full"] }
env_logger = "0.11.6"
uuid = { version = "1.11.0", features = ["v4", "fast-rng", "macro-diagnostics"] }