Signup overhaul: 11-12, SSO

[jacbn]

• Allows 11-12 users to log in to Ada via SSO.
• Reworks the SSO flow to direct back into the email signup flow, such that required account info is not left to the RAI modal after signing up.
• As a consequence, allows teachers to sign up directly on Ada with SSO, like they can for email
• Adjusts Ada user info collection to:
  • include required DoB, MM/YY only
  • require gender input
  • remove defaults for (non-assignment) email prefs; require users to pick values for news + events options
• Shifts user preferences before "Account created!" message (Ada)
• Adds "Account created!" message for Sci with graphic, to align the two flows more closely

[codecov]

Codecov Report

❌ Patch coverage is 37.98883% with 111 lines in your changes missing coverage. Please review.
✅ Project coverage is 43.20%. Comparing base (5e8f71b) to head (e3528ed).
⚠️ Report is 26 commits behind head on main.

Files with missing lines	Patch %	Lines
...rc/app/components/pages/RegistrationSetDetails.tsx	2.94%	33 Missing ⚠️
...p/components/pages/RegistrationAgeCheckSSOOnly.tsx	41.37%	17 Missing ⚠️
src/app/state/actions/index.tsx	8.33%	11 Missing ⚠️
...pp/components/handlers/ProviderCallbackHandler.tsx	11.11%	8 Missing ⚠️
.../app/components/elements/sidebar/SignupSidebar.tsx	12.50%	7 Missing ⚠️
src/app/components/pages/RegistrationAgeCheck.tsx	12.50%	7 Missing ⚠️
...rc/app/components/pages/RegistrationRoleSelect.tsx	16.66%	5 Missing ⚠️
...components/elements/inputs/TrueFalseRadioInput.tsx	55.55%	4 Missing ⚠️
src/app/components/pages/RegistrationSuccess.tsx	42.85%	4 Missing ⚠️
src/app/components/elements/inputs/DobInput.tsx	50.00%	2 Missing and 1 partial ⚠️
... and 7 more

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2262   +/-   ##
=======================================
  Coverage   43.20%   43.20%           
=======================================
  Files         601      602    +1     
  Lines       25757    25806   +49     
  Branches     8574     8616   +42     
=======================================
+ Hits        11128    11150   +22     
- Misses      14580    14597   +17     
- Partials       49       59   +10     

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