Update synthetic ID components and default template

[aram356]

Summary

Update the synthetic ID generation system to modify available components and change the default template.

Changes Required

Components to Keep

1. client_ip - Client IP address
2. user_agent - Browser user agent string
3. accept_language - Accept-Language header
4. accept_encoding - Accept-Encoding header (new)

Components to Add

• random_uuid - A random UUID for additional entropy

Components to Remove

• first_party_id - Remove from available components
• publisher_domain - Remove from available components
• auth_user_id - Remove from available components

New Default Template

{{ client_ip }}:{{ user_agent }}:{{ accept_language }}:{{ accept_encoding }}

Additional: Random Suffix

Append a random 6-character alphanumeric suffix (a-z, A-Z, 0-9) to the HMAC hash, separated by a period.

Final ID format: <64-char-hmac>.<6-char-random-suffix>

Example: a1748067b3908f2c9e0f6ea30a341328ba4b84de45448b13d1007030df14a98e.xK9f2B

Files to Update

• crates/common/src/synthetic.rs - Main synthetic ID generation logic
• trusted-server.toml - Default configuration and template documentation