feat: add proposal for application email generation

Add OpenSpec proposal for /write-application-email command that:
- Generates professional application emails with subject lines
- Verifies documents exist in attachments/ folder before generation
- Updates /new-application to create attachments/ subfolder
- Follows similar pattern to /write-cover-letter command

Specs:
- application-email: 9 requirements for email generation
- application-management: 3 requirements for folder structure

OpenSpec: add-application-email

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

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

openspec/changes/add-application-email/proposal.md

@@ -0,0 +1,28 @@
+# Add Application Email Generation
+
+## Why
+
+Users need a simple, automated way to compose professional application emails with proper subject lines and document references. Manually crafting these emails for every application is time-consuming and error-prone.
+
+## What Changes
+
+- Add `/write-application-email` command that generates email content and subject line
+- Command verifies required documents exist in `attachments/` folder before generation
+- Email references CV, cover letter, and optionally certificates/diplomas
+- Update `/new-application` command to create `attachments/` subfolder with `.keep` file
+- Follow similar implementation pattern to `/write-cover-letter` command
+
+## Impact
+
+**Affected specs:**
+- `application-email` (new capability)
+- `application-management` (modification to folder structure)
+
+**Affected code:**
+- `src/.claude/commands/new-application.md` - Add attachments folder creation
+- `src/.claude/commands/write-application-email.md` - New command file
+- `src/.claude/templates/` - Potentially new email template (if needed)
+
+**Out of scope:**
+- Creating or generating documents (CV, certificates) - must exist beforehand
+- Attachment handling beyond verification