UI/UX audit fixes: clickable pipelines, broken links, isActive locking

- Make pipeline cards clickable on list page (navigate to detail view)
- Fix broken nav link: applicant /messages → /mentor
- Fix broken nav link: mentor /messages → /projects
- Add isActive field locking to all 7 wizard sections (intake, main-track,
  filtering, assignment, awards, live-finals, notifications)
- Add minLoad ≤ maxLoad cross-field validation in assignment section
- Add duplicate stage slug detection in main track section
- Add active pipeline warning banners in intake and main track sections

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/app/(admin)/admin/rounds/pipeline/[id]/edit/page.tsx

@@ -309,6 +309,7 @@ export default function EditPipelinePage() {
             onChange={(c) =>
               updateStageConfig('INTAKE', c as unknown as Record<string, unknown>)
             }
+            isActive={isActive}
           />
         </WizardSection>
 
@@ -323,6 +324,7 @@ export default function EditPipelinePage() {
           <MainTrackSection
             stages={mainTrack?.stages ?? []}
             onChange={updateMainTrackStages}
+            isActive={isActive}
           />
         </WizardSection>
 
@@ -339,6 +341,7 @@ export default function EditPipelinePage() {
             onChange={(c) =>
               updateStageConfig('FILTER', c as unknown as Record<string, unknown>)
             }
+            isActive={isActive}
           />
         </WizardSection>
 
@@ -355,6 +358,7 @@ export default function EditPipelinePage() {
             onChange={(c) =>
               updateStageConfig('EVALUATION', c as unknown as Record<string, unknown>)
             }
+            isActive={isActive}
           />
         </WizardSection>
 
@@ -369,6 +373,7 @@ export default function EditPipelinePage() {
           <AwardsSection
             tracks={state.tracks}
             onChange={(tracks) => updateState({ tracks })}
+            isActive={isActive}
           />
         </WizardSection>
 
@@ -385,6 +390,7 @@ export default function EditPipelinePage() {
             onChange={(c) =>
               updateStageConfig('LIVE_FINAL', c as unknown as Record<string, unknown>)
             }
+            isActive={isActive}
           />
         </WizardSection>
 
@@ -403,6 +409,7 @@ export default function EditPipelinePage() {
             onOverridePolicyChange={(overridePolicy) =>
               updateState({ overridePolicy })
             }
+            isActive={isActive}
           />
         </WizardSection>