Summary

Normalize mixed-case profile names to lowercase in assign_task() so the Kanban dispatcher does not hit Invalid profile name errors when the dashboard UI passes title-cased assignees.

Root Cause

The dashboard UI may pass profile names with mixed case (e.g. Jules, Librarian) to kanban_db.assign_task(). These are stored as-is in the DB. Later, when dispatch_once() spawns a worker via hermes -p <assignee>, the CLI's validate_profile_name() rejects the name because the regex _PROFILE_ID_RE = r"^[a-z0-9][a-z0-9_-]{0,63}$" only accepts lowercase.

The task is never claimed, and the dispatcher error is:

Invalid profile name 'Jules'. Must match [a-z0-9][a-z0-9_-]{0,63}

Fix

• Add normalize_profile_name() in hermes_cli/profiles.py that lowercases names (preserving "default" and None).
• Call it in assign_task() before storing the assignee in the DB.

This is a one-line change in the hot path (profile = normalize_profile_name(profile)) plus the helper function.

Regression Coverage

• test_assign_task_normalizes_profile_to_lowercase — core regression: "Jules" → "jules"
• test_assign_task_normalizes_title_case_profile — "Librarian" → "librarian"
• test_assign_task_preserves_already_lowercase — idempotent for lowercase
• test_assign_task_preserves_default_special_case — "default" preserved
• test_assign_task_normalizes_none_passthrough — unassign still works
• 8 unit tests for normalize_profile_name() covering edge cases

Testing

scripts/run_tests.sh tests/hermes_cli/test_profiles.py tests/hermes_cli/test_kanban_db.py
# 143 passed

Closes #18498