UI polish: fix black-on-dark leftovers, spacing, unstyled elements ...

- theme.css: design tokens mirroring kit's hardcoded Tokyo Night palette
  (--ltt-* + --color-* aliases used by @ltt/ui and the overlay)
- CompactSelect: kit GnSelect is a 54px/600px form control — compact
  variant for toolbar filters and the report status select
- ProjectPage: filters were blank (null modelValue matches no <option>)
  and huge; drop the floating GnTable caption chip
- AppShell: empty topbar chip is now a user identity + logout; remove
  unused props
- ReportPage/ProjectsPage/SettingsPage: kit .card is width:max-content/
  max-width:340px — cards fill their grid now; toolbar shows localized
  project count; PageHeader on settings
- ElementContext/EnvironmentInfo: row separators, dim labels, formatted
  CAPTURED date, selector rendered as a code chip
- ScreenshotViewer: optional labels prop (panel passes i18n strings)
- i18n: ru plural rules ("1 проект"), no hardcoded EN strings on
  auth pages; hide kit's "Forgot password?" stub link
- extension overlay: define --color-* vars on the shadow mount point
- Makefile: ext:watch/ext:test targets never parsed (colon in
  .PHONY/rules) — renamed to ext-watch/ext-test
- shot.mjs: screenshot harness for visual review of all pages

Co-Authored-By: Claude Code <noreply@anthropic.com>