refactor: distribute Acaua as a Docker image instead of a desktop app

Acaua is a collective SOC daemon consuming only Zeek log files, not a
single-user tool needing local hardware like its siblings. Drop the
Tauri desktop shell, installers and self-update entirely; the server
and its web dashboard ship as a container, updated by pulling a new
image tag.

Link against the official prebuilt libduckdb instead of compiling it
from source via the bundled feature, cutting image build time from
15+ minutes to about 3. Fix a real bug found along the way: as PID 1
in a container, the daemon ignored SIGTERM and was always killed
after the stop timeout; it now shuts down gracefully.

Also corrects the Pillar 1 beaconing score: the period estimate had a
harmonic alias (a perfectly periodic 4h series resolved to 600s), and
the old score formula flagged pure random traffic as suspicious
(p95 = 0.839 on Poisson noise). The new formula was validated against
300 samples per scenario.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VAyr8d7HuAdUGB6aA5xmDD

apps/gui/ui/app.js

@@ -1,7 +1,6 @@
 import { setLang, tr } from './i18n.js';
 
 const $ = (selector) => document.querySelector(selector);
-const tauriInvoke = window.__TAURI__?.core?.invoke;
 
 const connection = $('#connection');
 const connectionText = $('#connectionText');
@@ -30,7 +29,6 @@ async function fetchJson(path, options = {}) {
 }
 
 async function call(command, args = {}) {
-  if (tauriInvoke) return tauriInvoke(command, args);
   switch (command) {
     case 'app_info':
       return fetchJson('/api/status');