Foundation: route, recharts, sprint-dates migration, chart-colors helper (#46)

* feat(ST-1201): add Sprint start_date/end_date + claude_jobs index migration

- Sprint model: optionele start_date en end_date (DATE) voor burndown x-as
- CREATE INDEX claude_jobs(status, finished_at) voor agent-throughput-queries
- Bestaande sprints houden NULL; burndown skipt die

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

* feat(ST-1202): add lib/chart-colors.ts + vitest coverage

MD3-token-to-CSS-var mappings for STATUS, PRIORITY, VERIFY, JOB_STATUS
and SERIES_COLORS; all 5 tests pass.

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

* feat(ST-1203): add Insights link to NavBar

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

* feat(ST-1204): move Insights NavBar link between Solo and Todo's

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

* feat(ST-1205): add sprint start_date/end_date UI + server actions

- createSprintAction + updateSprintDatesAction: Zod date validation
  with end_date >= start_date cross-check
- start-sprint-button: date inputs in create dialog
- sprint-header: date display button + edit dialog with updateSprintDatesAction
- sprint page: select start_date/end_date for SprintHeader prop
- Demo blokkade via bestaande isDemo checks
- 6 tests groen (validation + demo guard)

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

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

__tests__/lib/chart-colors.test.ts

@@ -0,0 +1,52 @@
+import { describe, it, expect } from 'vitest'
+import {
+  STATUS_COLORS,
+  PRIORITY_COLORS,
+  VERIFY_COLORS,
+  JOB_STATUS_COLORS,
+  SERIES_COLORS,
+} from '@/lib/chart-colors'
+
+describe('chart-colors', () => {
+  it('STATUS_COLORS has all TaskStatus keys and non-empty values', () => {
+    const keys: (keyof typeof STATUS_COLORS)[] = ['TO_DO', 'IN_PROGRESS', 'REVIEW', 'DONE']
+    for (const key of keys) {
+      expect(STATUS_COLORS[key]).toBeTruthy()
+      expect(typeof STATUS_COLORS[key]).toBe('string')
+    }
+  })
+
+  it('PRIORITY_COLORS has keys 1-4 with non-empty values', () => {
+    const keys = [1, 2, 3, 4] as const
+    for (const key of keys) {
+      expect(PRIORITY_COLORS[key]).toBeTruthy()
+      expect(typeof PRIORITY_COLORS[key]).toBe('string')
+    }
+  })
+
+  it('VERIFY_COLORS has all VerifyResult keys and non-empty values', () => {
+    const keys: (keyof typeof VERIFY_COLORS)[] = ['ALIGNED', 'PARTIAL', 'EMPTY', 'DIVERGENT']
+    for (const key of keys) {
+      expect(VERIFY_COLORS[key]).toBeTruthy()
+      expect(typeof VERIFY_COLORS[key]).toBe('string')
+    }
+  })
+
+  it('JOB_STATUS_COLORS has all ClaudeJobStatus keys and non-empty values', () => {
+    const keys: (keyof typeof JOB_STATUS_COLORS)[] = [
+      'queued', 'claimed', 'running', 'done', 'failed', 'cancelled',
+    ]
+    for (const key of keys) {
+      expect(JOB_STATUS_COLORS[key]).toBeTruthy()
+      expect(typeof JOB_STATUS_COLORS[key]).toBe('string')
+    }
+  })
+
+  it('SERIES_COLORS has 5 non-empty entries', () => {
+    expect(SERIES_COLORS).toHaveLength(5)
+    for (const color of SERIES_COLORS) {
+      expect(color).toBeTruthy()
+      expect(typeof color).toBe('string')
+    }
+  })
+})