feat: task time estimates and velocity chart on dashboard

- Added estimatedHours column to tasks schema
- Backend: create/update support for estimatedHours
- New /api/tasks/stats/velocity endpoint: daily completions, weekly velocity, estimate totals
- Dashboard: velocity chart with 7-day bar chart, this week count, avg/week, estimate summary
- TaskDetailPanel: estimated hours input field
- CreateTaskModal: estimated hours in advanced options
- TaskCard, KanbanBoard, TaskPage: estimate badge display

backend/src/db/schema.ts

@@ -82,6 +82,7 @@ export const tasks = pgTable("tasks", {
   assigneeName: text("assignee_name"),
   projectId: uuid("project_id").references(() => projects.id, { onDelete: "set null" }),
   dueDate: timestamp("due_date", { withTimezone: true }),
+  estimatedHours: integer("estimated_hours"),
   tags: jsonb("tags").$type<string[]>().default([]),
   subtasks: jsonb("subtasks").$type<Subtask[]>().default([]),
   progressNotes: jsonb("progress_notes").$type<ProgressNote[]>().default([]),

backend/src/routes/tasks.ts

@@ -154,6 +154,7 @@ export const taskRoutes = new Elysia({ prefix: "/api/tasks" })
           taskNumber: nextNumber,
           projectId: body.projectId || null,
           dueDate: body.dueDate ? new Date(body.dueDate) : null,
+          estimatedHours: body.estimatedHours ?? null,
           tags: body.tags || [],
           subtasks: [],
           progressNotes: [],
@@ -194,11 +195,70 @@ export const taskRoutes = new Elysia({ prefix: "/api/tasks" })
         ),
         projectId: t.Optional(t.Union([t.String(), t.Null()])),
         dueDate: t.Optional(t.Union([t.String(), t.Null()])),
+        estimatedHours: t.Optional(t.Union([t.Number(), t.Null()])),
         tags: t.Optional(t.Array(t.String())),
       }),
     }
   )
 
+  // GET stats - velocity and estimates - requires auth
+  .get("/stats/velocity", async ({ request, headers }) => {
+    await requireSessionOrBearer(request, headers);
+    
+    const allTasks = await db.select().from(tasks);
+    
+    // Build daily completion counts for last 14 days
+    const dailyCompletions: { date: string; count: number }[] = [];
+    for (let i = 13; i >= 0; i--) {
+      const d = new Date();
+      d.setDate(d.getDate() - i);
+      const dateStr = d.toISOString().split("T")[0];
+      const count = allTasks.filter(t => {
+        if (!t.completedAt) return false;
+        const completedDate = new Date(t.completedAt).toISOString().split("T")[0];
+        return completedDate === dateStr;
+      }).length;
+      dailyCompletions.push({ date: dateStr, count });
+    }
+    
+    // Estimate totals
+    const activeAndQueued = allTasks.filter(t => t.status === "active" || t.status === "queued");
+    const totalEstimated = activeAndQueued.reduce((sum, t) => sum + (t.estimatedHours || 0), 0);
+    const estimatedCount = activeAndQueued.filter(t => t.estimatedHours).length;
+    const unestimatedCount = activeAndQueued.length - estimatedCount;
+    
+    // Completed this week (Mon-Sun)
+    const now = new Date();
+    const dayOfWeek = now.getDay();
+    const mondayOffset = dayOfWeek === 0 ? 6 : dayOfWeek - 1;
+    const monday = new Date(now);
+    monday.setDate(monday.getDate() - mondayOffset);
+    monday.setHours(0, 0, 0, 0);
+    
+    const completedThisWeek = allTasks.filter(t => {
+      if (!t.completedAt) return false;
+      return new Date(t.completedAt) >= monday;
+    }).length;
+    
+    // Average tasks completed per week (last 4 weeks)
+    const fourWeeksAgo = new Date();
+    fourWeeksAgo.setDate(fourWeeksAgo.getDate() - 28);
+    const completedLast4Weeks = allTasks.filter(t => {
+      if (!t.completedAt) return false;
+      return new Date(t.completedAt) >= fourWeeksAgo;
+    }).length;
+    const avgPerWeek = Math.round((completedLast4Weeks / 4) * 10) / 10;
+    
+    return {
+      dailyCompletions,
+      completedThisWeek,
+      avgPerWeek,
+      totalEstimatedHours: totalEstimated,
+      estimatedTaskCount: estimatedCount,
+      unestimatedTaskCount: unestimatedCount,
+    };
+  })
+
   // GET single task by ID or number - requires session or bearer auth
   .get(
     "/:id",
@@ -242,6 +302,7 @@ export const taskRoutes = new Elysia({ prefix: "/api/tasks" })
       if (body.assigneeName !== undefined) updates.assigneeName = body.assigneeName;
       if (body.projectId !== undefined) updates.projectId = body.projectId;
       if (body.dueDate !== undefined) updates.dueDate = body.dueDate ? new Date(body.dueDate) : null;
+      if (body.estimatedHours !== undefined) updates.estimatedHours = body.estimatedHours;
       if (body.tags !== undefined) updates.tags = body.tags;
       if (body.subtasks !== undefined) updates.subtasks = body.subtasks;
       if (body.progressNotes !== undefined) updates.progressNotes = body.progressNotes;
@@ -273,6 +334,7 @@ export const taskRoutes = new Elysia({ prefix: "/api/tasks" })
         assigneeName: t.Optional(t.Union([t.String(), t.Null()])),
         projectId: t.Optional(t.Union([t.String(), t.Null()])),
         dueDate: t.Optional(t.Union([t.String(), t.Null()])),
+        estimatedHours: t.Optional(t.Union([t.Number(), t.Null()])),
         tags: t.Optional(t.Array(t.String())),
         subtasks: t.Optional(t.Array(t.Object({
           id: t.String(),