* web/templates/pgcreds.html: New Credentials card is now always
rendered; Add Credentials toggle button reveals the create form
(hidden by default). Shows a message when all system accounts
already have credentials. Previously the card was hidden when
UncredentialedAccounts was empty.
* internal/ui/ui.go: added ActorName string field to PageData;
added actorName(r) helper resolving username from JWT claims
via DB lookup, returns empty string if unauthenticated.
* internal/ui/handlers_*.go: all full-page PageData constructors
now pass ActorName: u.actorName(r).
* web/templates/base.html: nav bar renders actor username as a
muted label before the Logout button when logged in.
* web/static/style.css: added .nav-actor rule (muted grey, 0.85rem).
- Introduced `web/templates/` for HTMX-fragmented pages (`dashboard`, `accounts`, `account_detail`, `error_fragment`, etc.).
- Implemented UI routes for account CRUD, audit log display, and login/logout with CSRF protection.
- Added `internal/ui/` package for handlers, CSRF manager, session validation, and token issuance.
- Updated documentation to include new UI features and templates directory structure.
- Security: Double-submit CSRF cookies, constant-time HMAC validation, login password/Argon2id re-verification at all steps to prevent bypass.
