feat: component library, markdown renderer, multi-workspace dashboard

- Add PeerCardViewer with collapsible ALL_CAPS sections and title-case metadata table
- Add MarkdownRenderer (react-markdown + remark-gfm) with TimestampChip (Luxon)
- Add Badge, Card, Collapsible shadcn/ui components
- Rebuild Dashboard with per-workspace queue table and aggregate stats
- Add metadata.source chip to SessionList, observe_me badge to PeerList
- Make session_id in ConclusionBrowser a clickable link
- Fix sessionPeers pagination crash (unwrap .items from Page_Peer_ response)
- Add COLOR constants (src/lib/constants.ts) and localized formatCount (Intl)
- Fix dark mode contrast: text-2/3/4 vars, global font-size baseline

src/lib/constants.ts

@@ -0,0 +1,28 @@
+// Semantic color tokens for inline styles.
+// CSS variables (var(--text-1) etc.) handle theme-aware colors.
+// These constants are for fixed semantic states that don't invert with theme.
+
+export const COLOR = {
+	// Status
+	success: "#34d399",
+	successDim: "rgba(52,211,153,0.08)",
+	successBorder: "rgba(52,211,153,0.2)",
+
+	warning: "#f59e0b",
+	warningDim: "rgba(245,158,11,0.08)",
+	warningBorder: "rgba(245,158,11,0.2)",
+
+	destructive: "#f87171",
+	destructiveDim: "rgba(239,68,68,0.08)",
+	destructiveBorder: "rgba(239,68,68,0.2)",
+
+	// Accent (indigo — matches --accent CSS var)
+	accent: "#6366f1",
+	accentText: "#818cf8",
+	accentSoft: "#c7d2fe",
+	accentDim: "rgba(99,102,241,0.08)",
+	accentDimHover: "rgba(99,102,241,0.06)",
+	accentSubtle: "rgba(99,102,241,0.1)",
+	accentBorder: "rgba(99,102,241,0.2)",
+	accentBorderStrong: "rgba(99,102,241,0.15)",
+} as const;