Return value from getLastModified is not truncated to seconds

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Consider this servlet:

```kotlin
package org.acme

import jakarta.servlet.annotation.WebServlet
import jakarta.servlet.http.HttpServlet
import jakarta.servlet.http.HttpServletRequest
import jakarta.servlet.http.HttpServletResponse

@WebServlet(urlPatterns = ["/test"])
class TestServlet : HttpServlet() {
override fun doGet(req: HttpServletRequest, resp: HttpServletResponse) {
resp.contentType = "text/plain"
resp.writer.write("Hello")
}

override fun getLastModified(req: HttpServletRequest): Long {
return 1750746812123
}
}
```

Run up an application with this servlet then follow these steps:

1. Run `curl -v http://localhost:8080/test`.
2. Observe that the response includes the header `Last-Modified: Tue, 24 Jun 2025 06:33:32 GMT`.
3. Run `curl -v http://localhost:8080/test -H 'If-Modified-Since: Tue, 24 Jun 2025 06:33:32 GMT'`.

Expected result:

A 304 not modified response is returned.

Actual result:

A 200 response is returned.

If you then modify the servlet to return `1750746812000` from `getLastModified` then the last curl command returns the 304 as expected.

Compare your implementation to Tomcat’s for example; they truncate the value returned by `getLastModified` to the second before comparing it with the `If-Modified-Since` timestamp because that’s the precision of HTTP dates.

Start by locating the servlet handling for getLastModified and the comparison with the If-Modified-Since request header. Reproduce the behavior with the two curl commands from the report, then verify that a sub-second return value produces the expected 304 response.

Written by the indexing model from the issue text.