feat: implement application email generation command

Implement /write-application-email command and update folder structure:

Changes:
- Add /write-application-email command with document verification
- Update /new-application to create attachments/ subfolder with .keep file
- Update CLAUDE.md with comprehensive workflow documentation
- Add Example 5 showing email generation usage

Features:
- Verifies CV, cover letter exist in attachments/ before generation
- Generates brief professional email (3-4 sentences)
- Supports German/English language detection
- Adapts tone (Formal/Balanced/Casual) from application.md
- Professional subject line format
- Explicit document references
- Flags: --skip-validation, --force

File structure now includes:
applications/pending/[app-name]/
  ├── application.md
  ├── input/
  └── attachments/
      └── .keep

OpenSpec: add-application-email

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

src/CLAUDE.md

@@ -218,10 +218,37 @@ When helping with job applications, follow this comprehensive workflow:
 - Emphasize relevant experience from profile.md
 - Incorporate keywords naturally
 
-### 9. Generate Application Email (FUTURE)
-- Create professional application email (coming soon)
+### 9. Prepare Attachments
+- Convert generated documents to PDF if needed
+- Add final documents to `attachments/` folder:
+  - CV/Resume (PDF)
+  - Cover letter (PDF) - convert from cover-letter.md
+  - Certificates and diplomas (PDF) if required by job posting
 
-### 10. Quality Assurance
+### 10. Generate Application Email
+- Run `/write-application-email` to generate professional email with document references
+- System automatically:
+  - Validates application first (stops if incomplete)
+  - Verifies required documents exist in attachments/ folder (CV and cover letter minimum)
+  - Checks if application-email.md already exists (prevents overwriting)
+- Generates brief email (3-4 sentences) including:
+  - Professional subject line (format: "Application for [Job Title] - [Your Name]")
+  - Brief introduction and interest statement
+  - Explicit reference to all attached documents
+  - Contact information and availability statement
+- Applies appropriate tone (Formal/Balanced/Casual) from application.md
+- Detects and applies correct language (German/English)
+- Saves to `application-email.md` in application folder
+- Flags available: `--skip-validation`, `--force` (overwrite existing)
+
+### 11. Review Application Email
+- Read generated application-email.md
+- Verify all attachments are correctly listed
+- Ensure subject line is appropriate
+- Check contact information is current
+- Confirm tone matches company culture
+
+### 12. Quality Assurance
 - Verify all company names, dates, and facts are correct
 - Ensure consistency between all documents (CV ↔ cover letter ↔ email)
 - Check that tone matches the target company culture
@@ -253,11 +280,25 @@ When helping with job applications, follow this comprehensive workflow:
   - Word count target enforcement (300-400 words)
   - Factual accuracy verification
 
-### Application Email
-- Keep it short (3-4 sentences maximum)
-- Subject line: Clear and professional
-- Body: Brief introduction, reference to attached documents, expression of interest
-- Professional signature using contact info from `profile.md`
+### Application Email (Generated by `/write-application-email`)
+- **Structure**: Subject → Greeting → Brief body (3-4 sentences) → Sign-off with contact info
+- **Length**: 3-4 sentences maximum (the cover letter contains the details)
+- **Tone**: Applied from application.md tone assessment (Formal/Balanced/Casual)
+- **Language**: Inferred from job posting context (German/English)
+- **Content**:
+  - Professional subject line: "Application for [Job Title] - [Your Name]"
+  - Brief statement of purpose (applying for the position)
+  - Explicit reference to attached documents (CV, cover letter, certificates)
+  - One sentence showing interest or fit
+  - Availability for interview/discussion
+- **Document Verification**:
+  - Automatic check that CV and cover letter exist in attachments/ folder
+  - Lists all documents that will be attached
+  - Stops generation if required documents are missing
+- **Quality checks**:
+  - Automatic validation before generation
+  - Protection against overwriting existing work
+  - Verification that attachments folder contains required documents
 
 ## Cultural Considerations
 
@@ -290,10 +331,11 @@ Adjust recommendations based on the target market if the user specifies a differ
 ## Available Commands
 
 - `/validate-profile` - Validate that `profile.md` is complete and ready for application generation
-- `/new-application "Company - Job Title"` - Create a new application workspace with organized folder structure
+- `/new-application "Company - Job Title"` - Create a new application workspace with organized folder structure (includes attachments/ folder)
 - `/populate-application` - Analyze input documents and populate application.md with job info, research, and strategy
 - `/validate-application [optional-app-name]` - Validate that application.md is complete before document generation
 - `/write-cover-letter [optional-app-name] [--skip-validation] [--force]` - Generate a tailored cover letter based on application strategy
+- `/write-application-email [optional-app-name] [--skip-validation] [--force]` - Generate a professional application email with document references
 
 ## Example Usage
 
@@ -310,7 +352,9 @@ Adjust recommendations based on the target market if the user specifies a differ
 6. Validation step: "Run `/validate-application` to ensure the application is complete"
 7. If validation passes: "Generate cover letter with `/write-cover-letter`"
 8. After generation: "Review cover-letter.md and personalize as needed"
-9. Future: Generate tailored CV and application email
+9. Document preparation: "Convert cover-letter.md to PDF and add it along with your CV to the `attachments/` folder"
+10. Email generation: "Generate application email with `/write-application-email`"
+11. Final review: "Review application-email.md, verify all documents are listed correctly, and you're ready to send!"
 
 ### Example 2: Quick Document Request (Legacy Flow)
 
@@ -364,6 +408,39 @@ Adjust recommendations based on the target market if the user specifies a differ
 3. Proceeds with generation
 4. Suggests: "Review the new version and keep whichever you prefer"
 
+### Example 5: Generating an Application Email
+
+**User**: "Generate application email for my TechCorp application"
+
+**Claude Code should**:
+1. If user is in application folder: Run `/write-application-email` (auto-detects location)
+2. If user is elsewhere: Run `/write-application-email 2025-11-02-TechCorp-Software-Engineer`
+3. System automatically validates application first:
+   - If validation fails: Stop and show errors, suggest fixing or using `--skip-validation`
+   - If validation passes: Proceed to document verification
+4. System verifies documents in attachments/ folder:
+   - Check for CV/Resume file
+   - Check for cover letter file
+   - Check for optional certificates
+   - If required documents missing: Stop and show clear error with guidance
+   - If documents found: Proceed to generation
+5. Generate application email:
+   - Read profile.md for applicant contact information
+   - Read application.md for job details and tone
+   - Generate brief email (3-4 sentences) with professional subject line
+   - Include explicit references to all attached documents
+   - Save to application-email.md
+6. Show success: "✅ Application email saved: application-email.md. Attachments ready: CV.pdf, Cover_Letter.pdf. Next: Review and send."
+
+**User**: "There's no CV in attachments folder"
+
+**Claude Code should**:
+1. System detects missing CV during verification step
+2. Show error: "❌ CV/Resume not found in attachments folder"
+3. List what was found and what's missing
+4. Provide guidance: "Please add your CV to: applications/pending/[folder]/attachments/"
+5. Suggest filename conventions: "Tip: Filename should contain 'cv', 'resume', or 'lebenslauf'"
+
 ## Updating the Profile
 
 If you notice missing or outdated information during application preparation: