Decouple projects from rounds with RoundProject join table

Projects now exist at the program level instead of being locked to a
single round. A new RoundProject join table enables many-to-many
relationships with per-round status tracking. Rounds have sortOrder
for configurable progression paths.

- Add RoundProject model, programId on Project, sortOrder on Round
- Migration preserves existing data (roundId -> RoundProject entries)
- Update all routers to query through RoundProject join
- Add assign/remove/advance/reorder round endpoints
- Add Assign, Advance, Remove Projects dialogs on round detail page
- Add round reorder controls (up/down arrows) on rounds list
- Show all rounds on project detail page

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

prisma/cleanup-dummy.ts

@@ -8,15 +8,15 @@ async function cleanup() {
   // Find and delete the dummy round
   const dummyRound = await prisma.round.findFirst({
     where: { slug: 'round-1-2026' },
-    include: { projects: true }
+    include: { roundProjects: { include: { project: true } } }
   })
 
   if (dummyRound) {
     console.log(`Found dummy round: ${dummyRound.name}`)
-    console.log(`Projects in round: ${dummyRound.projects.length}`)
+    console.log(`Projects in round: ${dummyRound.roundProjects.length}`)
 
     // Get project IDs to delete
-    const projectIds = dummyRound.projects.map(p => p.id)
+    const projectIds = dummyRound.roundProjects.map(rp => rp.projectId)
 
     // Delete team members for these projects
     if (projectIds.length > 0) {
@@ -25,11 +25,11 @@ async function cleanup() {
       })
       console.log(`Deleted ${teamDeleted.count} team members`)
 
-      // Disconnect projects from round first
-      await prisma.round.update({
-        where: { id: dummyRound.id },
-        data: { projects: { disconnect: projectIds.map(id => ({ id })) } }
+      // Delete round-project associations
+      await prisma.roundProject.deleteMany({
+        where: { roundId: dummyRound.id }
       })
+      console.log(`Deleted round-project associations`)
 
       // Delete the projects
       const projDeleted = await prisma.project.deleteMany({