feat: browser session persistence, auto-screenshots, context optimization, user cleanup

Browser tool:
- Session-persistent Chrome tab (same tab reused across all calls in a pentest)
- Auto-screenshot on every navigate and click (stored in attack chain for report)
- Fill uses CDP Input.insertText (fixes WebSocket corruption on special chars)
- Switched from browserless/chromium to chromedp/headless-shell (stable WS)

Context window optimization:
- Strip screenshot_base64 from LLM conversation (kept in DB for report)
- Truncate HTML to 2KB, page text to 1.5KB in LLM messages
- Cap element/link arrays at 15 items
- SAST triage: batch 30 findings per LLM call instead of all at once

Report improvements:
- Auto-embed screenshots in attack chain timeline (navigate + click nodes)
- Cover page shows best app screenshot
- Attack chain phases capped at 8 (no more 20x "Final")

User cleanup:
- TestUserRecord model tracks created test users per session
- cleanup.rs: Keycloak (Admin REST API), Auth0 (Management API), Okta (Users API)
- Auto-cleanup on session completion when cleanup_test_user is enabled
- Env vars: KEYCLOAK_ADMIN_USERNAME, KEYCLOAK_ADMIN_PASSWORD

System prompt:
- Explicit browser usage instructions (navigate → get_content → click → fill)
- SPA auth bypass guidance (check page content, not HTTP status)
- Screenshot instructions for evidence collection

Other:
- Pin mongo:7 in docker-compose (mongo:latest/8 segfaults on kernel 6.19)
- Add deploy/docker-compose.mailserver.yml for Postfix + Dovecot

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

compliance-agent/src/pentest/report/html/attack_chain.rs

@@ -149,6 +149,23 @@ fn build_chain_html(chain: &[AttackChainNode]) -> String {
                 )
             };
 
+            // Render inline screenshot if this is a browser screenshot action
+            let screenshot_html = if node.tool_name == "browser" {
+                node.tool_output
+                    .as_ref()
+                    .and_then(|out| out.get("screenshot_base64"))
+                    .and_then(|v| v.as_str())
+                    .filter(|s| !s.is_empty())
+                    .map(|b64| {
+                        format!(
+                            r#"<div class="step-screenshot"><img src="data:image/png;base64,{b64}" alt="Browser screenshot" style="max-width:100%;border:1px solid #e2e8f0;border-radius:6px;margin-top:8px;"/></div>"#
+                        )
+                    })
+                    .unwrap_or_default()
+            } else {
+                String::new()
+            };
+
             chain_html.push_str(&format!(
                 r#"<div class="step-row">
                         <div class="step-num">{num}</div>
@@ -161,6 +178,7 @@ fn build_chain_html(chain: &[AttackChainNode]) -> String {
                                 {risk_badge}
                             </div>
                             {reasoning_html}
+                            {screenshot_html}
                         </div>
                     </div>"#,
                 num = i + 1,