feat(contacts): add support for additional fields (urls, org, note, custom)

[phuctm97]

Summary

Adds support for additional contact fields in gog contacts create and gog contacts update commands.

New Flags

Flag	Description
--org	Organization/company name
--title	Job title
--url	URL (can be repeated for multiple URLs)
--note	Note/biography
--custom	Custom field as key=value (can be repeated)

Usage Examples

# Create contact with organization and URLs
gog contacts create --given "Vu" --family "Nguyen" \
  --email "vu@example.com" \
  --org "SparkNamer" --title "Co-founder" \
  --url "https://github.com/tricknguyen" \
  --url "https://linkedin.com/in/vu" \
  --note "Met at HRG batch 0"

# Add custom fields
gog contacts create --given "John" --family "Doe" \
  --custom "github=johndoe" \
  --custom "telegram=@johnd"

# Update existing contact
gog contacts update people/c123 \
  --org "New Company" \
  --url "https://newsite.com"

Changes

• Updated ContactsCreateCmd and ContactsUpdateCmd structs with new fields
• Updated contactsReadMask to include organizations,urls
• Updated contactsGetReadMask to include biographies,userDefined
• Added helper functions: primaryOrganization, primaryURL, allURLs, primaryBio, userDefinedFields
• Updated ContactsGetCmd to display new fields

Tests

All existing tests pass.

Closes #198