feat: add Citations and WatchlistChat components, integrate with API

- Implemented Citations component to display citation data.
- Created WatchlistDrawer and ChatSidebar components for managing watchlists and AI chat functionality.
- Integrated API calls for watchlist management and chat interactions.
- Updated index.tsx to include new components in the main application layout.
- Added API client in lib/api.ts for structured API interactions.
- Developed Alerts, Dashboard, Portfolio, Routines, Screener, and Report pages with relevant data fetching and UI components.
- Introduced styles in tokens.css for consistent theming across the application.
- Configured TypeScript and Vite for project setup and development.

backend/internal/model/types.go

@@ -0,0 +1,74 @@
+// Package model holds shared domain types: citations, snapshots, agent
+// results. Every number in user-visible output carries a Citation.
+// API response shapes live in internal/sectors; agent inputs in internal/agents.
+package model
+
+import "time"
+
+// Citation pins a value to its source endpoint + snapshot timestamp.
+// Stale (>1 session old) citations are rendered marked, never hidden.
+type Citation struct {
+	Endpoint   string `json:"endpoint"`
+	SnapshotAt string `json:"snapshot_at"`
+	Ticker     string `json:"ticker,omitempty"`
+	Stale      bool   `json:"stale,omitempty"`
+}
+
+// Value is a cited number or string shown to users.
+type Value struct {
+	Label     string     `json:"label"`
+	Display   string     `json:"display"`
+	Citations []Citation `json:"citations"`
+}
+
+// Snapshot is one raw Sectors payload row.
+type Snapshot struct {
+	ID        int64
+	Ticker    string
+	Date      string
+	Source    string
+	Payload   string
+	FetchedAt time.Time
+}
+
+// AgentResult is the common output contract for A1..A7.
+type AgentResult struct {
+	Agent     string         `json:"agent"`
+	Score     float64        `json:"score"`
+	Summary   string         `json:"summary"`
+	Values    []Value        `json:"values"`
+	Flags     []string       `json:"flags"`
+	Citations []Citation     `json:"citations"`
+	Extra     map[string]any `json:"extra,omitempty"`
+}
+
+// Cite builds a Citation for one endpoint + snapshot date.
+func Cite(endpoint, ticker, snapshotAt string) Citation {
+	return Citation{Endpoint: endpoint, SnapshotAt: snapshotAt, Ticker: ticker}
+}
+
+// StaleSession returns the date before which snapshots count as stale:
+// anything older than the session containing ref (WIB trading day).
+func StaleSession(ref time.Time) time.Time {
+	y, m, d := ref.Date()
+	return time.Date(y, m, d, 0, 0, 0, 0, ref.Location()).AddDate(0, 0, -1)
+}
+
+// MarkStale flags citations older than cutoff (one session back).
+func MarkStale(citations []Citation, cutoff time.Time) []Citation {
+	out := make([]Citation, len(citations))
+	for i, c := range citations {
+		if t, err := time.Parse("2006-01-02", head10(c.SnapshotAt)); err == nil && t.Before(cutoff) {
+			c.Stale = true
+		}
+		out[i] = c
+	}
+	return out
+}
+
+func head10(s string) string {
+	if len(s) > 10 {
+		return s[:10]
+	}
+	return s
+}