redesign: Layout2 design-system + dashboard/tasks rework + perf

Design system (Layout2):
- Solid token-driven theme (no animated grid); single-source tokens for bg,
  cards (bg/border/radius), popups, fonts (Inter), and full semantic +
  data-viz color palette. Swept ~168 hardcoded colors to tokens.

Dashboard:
- Reflow: To Do + Calendar row (fixed right rail) over Activity / In-Progress /
  Team Performance; CSS height-match (To Do = Calendar); responsive stacking.
- 'Tasks Not Started' -> 'To Do' card with R#/Assigned columns; compact money fmt.

Tasks page:
- Combined tabs into Tasks + Completed with a Status column.
- Column-header sort + filter (Status, R#/new-vs-revision, Project, Task Type,
  Company) via portaled, scrollable FilterDropdown; removed toolbar filters and
  the projects side panel; headers stay visible when empty; renamed to 'Tasks'.

Perf:
- FK/filter index migration; removed redundant client/external scope waterfall
  (rely on RLS); parallel follow-up queries.

Mobile:
- Responsive grids; mobile topbar = hamburger only, blends with bg, proper offset.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/components/FileAttachment.jsx

@@ -103,7 +103,7 @@ export default function FileAttachment({ files, onChange }) {
           {files.map((file, i) => (
             <div key={i} style={{
               display: 'flex', alignItems: 'center', justifyContent: 'space-between',
-              padding: '7px 12px', background: 'var(--card-bg)', borderRadius: 4, border: '1px solid var(--border)',
+              padding: '7px 12px', background: 'var(--card-bg)', borderRadius: 4, border: 'var(--card-border)',
             }}>
               <div style={{ display: 'flex', alignItems: 'center', gap: 8 }}>
                 <span>📄</span>