docs(epic-3): add tech spec and story drafts for PDF Export

Epic 3: PDF Export - Planning Phase Complete

Tech Spec:
- Create tech-spec-epic-3.md with 10 acceptance criteria
- Define API contracts, workflows, and NFRs
- Document dependencies (puppeteer, @sparticuz/chromium)
- Add Vercel deployment configuration
- Include traceability mapping and test strategy

Story Drafts:
- 3-1: Create PDF Generation API Route (8 ACs, Puppeteer integration)
- 3-2: Create PDF Download Composable (8 ACs, download logic)
- 3-3: Connect Download Button to PDF Generation (8 ACs, integration)

Sprint Status Updates:
- epic-3: backlog → contexted
- All 3 stories: backlog → drafted

Files Created:
- docs/sprint-artifacts/tech-spec-epic-3.md
- docs/sprint-artifacts/3-1-create-pdf-generation-api-route.md
- docs/sprint-artifacts/3-2-create-pdf-download-composable.md
- docs/sprint-artifacts/3-3-connect-download-button-to-pdf-generation.md

Files Modified:
- docs/sprint-artifacts/sprint-status.yaml

Ready for: Story context generation or implementation

docs/sprint-artifacts/3-1-create-pdf-generation-api-route.md

@@ -0,0 +1,175 @@
+# Story 3.1: Create PDF Generation API Route
+
+Status: drafted
+
+## Story
+
+As a system,
+I want a server endpoint that generates PDF from the resume page,
+so that users get consistent, high-quality PDF output.
+
+## Acceptance Criteria
+
+1. **AC1:** Given a GET request to `/api/resume/pdf`, when the server processes the request, then it returns a PDF binary with Content-Type `application/pdf`
+2. **AC2:** Response includes `Content-Disposition: attachment; filename="Ali_Arghyani_Resume.pdf"`
+3. **AC3:** PDF matches the web preview exactly (WYSIWYG)
+4. **AC4:** PDF text is selectable and copy-able (ATS-compatible)
+5. **AC5:** PDF is A4 format (210mm × 297mm)
+6. **AC6:** PDF generation completes in under 3 seconds
+7. **AC7:** Given an error occurs, when caught, then it returns status 500 with JSON error message
+8. **AC8:** Timeout is set to 10 seconds max
+
+## Tasks / Subtasks
+
+- [ ] Create API route file (AC: #1, #2)
+  - [ ] Create `server/api/resume/pdf.get.ts`
+  - [ ] Set up Nuxt event handler with `defineEventHandler`
+  - [ ] Configure response headers (Content-Type, Content-Disposition)
+
+- [ ] Implement Puppeteer PDF generation (AC: #3-#6)
+  - [ ] Import puppeteer (dev) or puppeteer-core + chromium (prod)
+  - [ ] Get base URL from request headers
+  - [ ] Launch browser in headless mode
+  - [ ] Navigate to `/resume?print=true`
+  - [ ] Wait for `networkidle0` (fonts loaded)
+  - [ ] Generate PDF with options: format A4, printBackground true
+  - [ ] Close browser in finally block
+  - [ ] Return PDF buffer
+
+- [ ] Add error handling (AC: #7, #8)
+  - [ ] Wrap in try-catch block
+  - [ ] Set timeout to 10 seconds
+  - [ ] Return 500 status with error JSON on failure
+  - [ ] Log errors to console
+
+- [ ] Configure for Vercel deployment
+  - [ ] Use environment detection for puppeteer vs puppeteer-core
+  - [ ] Import @sparticuz/chromium for production
+  - [ ] Update vercel.json with function config (memory: 1024, maxDuration: 10)
+
+- [ ] Test API endpoint
+  - [ ] Test locally with `curl` or browser
+  - [ ] Verify PDF opens correctly
+  - [ ] Check text is selectable
+  - [ ] Measure generation time
+  - [ ] Test error handling
+
+## Dev Notes
+
+### Architecture Alignment
+
+**From Architecture Doc:**
+- File location: `server/api/resume/pdf.get.ts`
+- Uses Puppeteer server-side (ADR-001)
+- Navigates to `/resume?print=true` for WYSIWYG
+- Returns PDF buffer with proper headers
+
+**From Tech Spec Epic 3:**
+- AC1-AC4 map to this story
+- Performance target: < 3 seconds
+- Memory limit: 1024MB on Vercel
+
+### Implementation Notes
+
+**Local Development (puppeteer with bundled Chromium):**
+```typescript
+import puppeteer from 'puppeteer'
+
+const browser = await puppeteer.launch({
+  headless: true
+})
+```
+
+**Production (Vercel with @sparticuz/chromium):**
+```typescript
+import puppeteer from 'puppeteer-core'
+import chromium from '@sparticuz/chromium'
+
+const browser = await puppeteer.launch({
+  args: chromium.args,
+  executablePath: await chromium.executablePath(),
+  headless: chromium.headless
+})
+```
+
+**PDF Generation Options:**
+```typescript
+const pdf = await page.pdf({
+  format: 'A4',
+  printBackground: true,
+  margin: { top: 0, right: 0, bottom: 0, left: 0 }
+})
+```
+
+**Response Headers:**
+```typescript
+setResponseHeaders(event, {
+  'Content-Type': 'application/pdf',
+  'Content-Disposition': 'attachment; filename="Ali_Arghyani_Resume.pdf"'
+})
+```
+
+### Dependencies
+
+**Install:**
+```bash
+pnpm add puppeteer puppeteer-core @sparticuz/chromium
+```
+
+**vercel.json:**
+```json
+{
+  "functions": {
+    "server/api/resume/pdf.get.ts": {
+      "memory": 1024,
+      "maxDuration": 10
+    }
+  }
+}
+```
+
+### Testing Checklist
+
+- [ ] API returns PDF binary
+- [ ] Content-Type is application/pdf
+- [ ] Content-Disposition has correct filename
+- [ ] PDF opens in viewer
+- [ ] Text is selectable in PDF
+- [ ] Colors are correct (blue headers)
+- [ ] Generation time < 3 seconds
+- [ ] Error returns 500 with JSON
+- [ ] Works on Vercel deployment
+
+### References
+
+- [Source: docs/architecture.md#API-Contracts]
+- [Source: docs/architecture.md#Novel-Pattern-WYSIWYG-PDF-Export]
+- [Source: docs/architecture.md#Deployment-Architecture]
+- [Source: docs/sprint-artifacts/tech-spec-epic-3.md#AC1-AC4]
+
+## Dev Agent Record
+
+### Context Reference
+
+<!-- Will be filled by SM agent -->
+
+### Agent Model Used
+
+<!-- Will be filled by dev agent -->
+
+### Debug Log References
+
+<!-- Will be filled by dev agent during implementation -->
+
+### Completion Notes List
+
+<!-- Will be filled by dev agent after completion -->
+
+### File List
+
+<!-- Will be filled by dev agent with created/modified files -->
+
+---
+
+**Change Log:**
+- 2025-12-01: Story drafted by SM agent (Bob)