PBI-47: schema, pause_context Zod, resumePausedSprintRunAction, PAUSED-banner UI (#137)

Scrum4Me-side counterpart of scrum4me-mcp@f7f5a48 (PBI-9 + PBI-47):

- prisma migration: ClaudeJob.{base_sha,head_sha} + SprintRun.pause_context
- lib/pause-context.ts: Zod schema + parsePauseContext + pauseReasonLabel
  helper; single source of truth for the JSON pause_context shape produced
  by the mcp sprint-run flow (MERGE_CONFLICT pause)
- actions/sprint-runs.ts: resumePausedSprintRunAction — separate from the
  existing FAILED-resume flow, requires SprintRun.status === PAUSED, closes
  the linked ClaudeQuestion, clears pause_context, sets RUNNING/QUEUED based
  on whether a claim is still active
- components/sprint/sprint-run-controls.tsx: PAUSED banner with reason label,
  PR link, conflict-files list (max 5 + "+N more"), Resume button with
  confirm() guard
- app/(app)/products/[id]/sprint/page.tsx: load pause_context from active
  SprintRun and pass through to SprintRunControls

All MD3 tokens (warning-container, on-warning-container, primary). No raw
Tailwind utility colours.

Tests: 532 passing across 72 files (Scrum4Me side).

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

lib/pause-context.ts

@@ -0,0 +1,30 @@
+import { z } from 'zod'
+
+export const PauseReasonSchema = z.enum(['MERGE_CONFLICT'])
+export type PauseReason = z.infer<typeof PauseReasonSchema>
+
+export const PauseContextSchema = z.object({
+  pause_reason: PauseReasonSchema,
+  pr_url: z.string().url(),
+  pr_head_sha: z.string().min(7),
+  conflict_files: z.array(z.string()).default([]),
+  claude_question_id: z.string().min(1),
+  resume_instructions: z.string().min(1),
+  paused_at: z.string().datetime(),
+})
+
+export type PauseContext = z.infer<typeof PauseContextSchema>
+
+export function parsePauseContext(raw: unknown): PauseContext | null {
+  if (raw === null || raw === undefined) return null
+  const parsed = PauseContextSchema.safeParse(raw)
+  return parsed.success ? parsed.data : null
+}
+
+const PAUSE_REASON_LABELS: Record<PauseReason, string> = {
+  MERGE_CONFLICT: 'Merge-conflict op PR',
+}
+
+export function pauseReasonLabel(reason: PauseReason): string {
+  return PAUSE_REASON_LABELS[reason] ?? reason
+}