All messages view search improvements

[mauroservienti]

Describe the suggested improvement

Is your improvement related to a problem? Please describe.

On large databases, the all messages view search behavior is suboptimal and could benefit from several improvements

Describe the suggested solution

Since when landing on the page an unfiltered search is performed immediately, when the database is large (500 GB+) this operation takes several seconds; Ideally:

• There should be a cancel button to allow users to stop the default search request
• Or, the default query should be "show only the last 6 hours" of messages
• Or, there should be no search automatically performed to begin with

In addition to those, we should be looking at:

• In its current configuration, when changing a query parameter it executes immediately, and on large database it takes several seconds, which is suboptimal if the goal is to tweak more than one parameter.
• While a query is executed server side, the UI is all greyed out and blocked; it should not, users should be able to change their mind, the current query should be canceled and the new one executed.
• The datetime picker default behavior uses the current time, and that is confusing, by default it should be midnight UTC or Local time and only if users look for a specific time range they decide what that is
• The datetime picker should support not only dates but also Last day, Last 15 minutes, Last 6 hours, etc. and the UI should support adjusting the default period at minimum in browser local storage.
• Highlight rows added by auto-refresh. With auto-refresh on, a refresh that brings in new messages is invisible — the list just repaints. Give rows that weren't present in the previous result a brief background fade so the change is visible at a glance.
• Keyboard shortcuts. / focuses the search input (common convention: GitHub, Grafana); Esc cancels the running query — the keyboard equivalent of the refresh-button-as-cancel. Both are view-local and need no discoverability UI beyond a tooltip.
• Copy-link button for the current query. The URL already carries the full query, including live time-range expressions like from=now-6h, so a pasted link re-evaluates the window instead of going stale. A small "copy link"
  control next to the results line would make that shareability discoverable — today you have to know to copy the address bar.
• Improve the responsive design, making the view less wide currently not result in a very great layout experience.

Additional Context

No response