fix(ui): unify Session navigation and restore uniform tab borders

PROJECT_STATE.md

@@ -48,6 +48,20 @@ PSD Gitea push and production deployment are still pending.
 
 ## Current product shape
 
+### Unified Session entry and complete tab borders — 2026-09-13
+
+The sidebar has one Session/Sessione button: return to the current unfinished
+session (including pending creation) without resetting/reconnecting it; otherwise
+prepare a new question with existing readiness and dirty-edit guards. Creation
+still requires submitting a question. A cold document panel is not a running session.
+Session tabs now have 11px horizontal/3px vertical padding, at least 38px height,
+and matching 1px borders on every side (gray inactive, red active), with no shared
+baseline or overlapping bottom border. This supersedes the earlier border removal.
+757 frontend tests, 15 browser scenarios, typecheck, i18n and Docker build pass.
+Mac frontend `2844778d311c`, image `d58dccfee3f9`, is healthy; only that service
+was recreated. Core/data services are unchanged, with no Omics or server deploy.
+Rollback image: `thothii-frontend:before-session-navigation-20260913`.
+
 ### Login copy and language-selector focus — 2026-09-13
 
 Removed the redundant login eyebrow/icon and installation-account explanation;
@@ -333,7 +347,8 @@ schema, Evidence, and vector mutation commands are retired.
 
 The right Administration sidebar invokes that same operation for the selected workspace. It shows
 only current readiness or the latest bounded failure diagnostic; there is no preprocessing history.
-Known non-ready state disables **New session**, while backend admission remains authoritative.
+Known non-ready state disables **Session** when it would start a new question,
+while backend admission remains authoritative.
 The same control exposes an inline-confirmed **Clear** action to remove replaceable reference
 vectors, LSH, corpus, and checkpoints while preserving the separate Memory collection. The host CLI
 equivalent is `workspace preprocess clear`.