Add complete XML doc and Swagger annotations to all controller endpoints

Every public action now has <summary>, <param>, and <returns> XML docs
plus matching SwaggerOperation/SwaggerResponse attributes with typed response
descriptions. Class-level summaries added to CvController, JobSearchController,
and RagController. Explanatory inline comments removed from FileDownloadController
per project conventions.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Apis/api/Controllers/CaptchaController.cs

@@ -29,8 +29,10 @@ namespace Api.Controllers
         /// <summary>
         /// Returns the public reCAPTCHA site key used by the client to render the widget.
         /// </summary>
+        /// <returns>200 OK with the configured public site key as a plain string.</returns>
         [HttpGet]
-        [SwaggerOperation(Summary = "Get captcha site key")]
+        [SwaggerOperation(Summary = "Get captcha public key", Description = "Returns the public reCAPTCHA site key required by the frontend to render the challenge widget.")]
+        [SwaggerResponse(StatusCodes.Status200OK, "Public site key returned")]
         [ProducesResponseType(StatusCodes.Status200OK)]
         public IActionResult GetSiteKey()
         {
@@ -38,13 +40,20 @@ namespace Api.Controllers
         }
 
         /// <summary>
-        /// Verify a captcha token and return the verification verdict.
+        /// Verifies a reCAPTCHA token submitted by the client and returns the full verification verdict.
         /// </summary>
+        /// <param name="req">The verification request containing the token and optional expected action name.</param>
+        /// <param name="ct">Cancellation token.</param>
+        /// <returns>
+        /// 200 OK with the full captcha verdict when verification passes;
+        /// 400 Bad Request with an <see cref="ErrorResponse"/> if the token is missing or verification fails.
+        /// </returns>
         [HttpPost("verify")]
-        [SwaggerOperation(Summary = "Verify captcha token")]
+        [SwaggerOperation(Summary = "Verify captcha token", Description = "Verifies a reCAPTCHA token and returns the provider verdict including the score.")]
+        [SwaggerResponse(StatusCodes.Status200OK, "Token verified successfully")]
+        [SwaggerResponse(StatusCodes.Status400BadRequest, "Token missing or verification failed", typeof(ErrorResponse))]
         [ProducesResponseType(StatusCodes.Status200OK)]
         [ProducesResponseType(typeof(ErrorResponse), StatusCodes.Status400BadRequest)]
-        [SwaggerResponse(StatusCodes.Status400BadRequest, "Captcha verification failed or token missing", typeof(ErrorResponse))]
         public async Task<IActionResult> Verify([FromBody] CaptchaVerifyRequest req, CancellationToken ct)
         {
             if (req is null || string.IsNullOrWhiteSpace(req.Token))