Use exact profile ages and remove pronouns

[ShaalaXIV]

Summary

• replace the profile age bracket with an optional exact numeric age
• remove pronouns from the editor, display, shared contract, and database
• safely clear legacy age-category ordinals during migration
• bump Beacon to 0.1.7 and protocol 3

Verification

• full release verifier passed
• server contract and protocol guard passed
• restart persistence smoke test passed
• legacy SQLite migration verified with integrity_check=ok
• EF model has no pending changes