refactor: convert profile to react-query and remove Redux

[arbrandes]

Description

Replaces the Redux stack (redux, react-redux, redux-saga, redux-thunk, reselect and their dev tooling) with @tanstack/react-query. The account, preferences, certificates and country allow-list become per-resource queries, the saves and photo changes become mutations that patch the cache, and the shared form state (the open field, drafts, per-field errors, save status) moves to a React context. services.js is renamed to api.js, as in Learner Dashboard and Account. The QueryClientProvider in index.jsx is temporary: the frontend-base conversion (#1405) removes it in favor of the shell's.

This is the first PR in the stack described in #1246, done on the current codebase so it can be reviewed separately from the frontend-base conversion, as openedx/frontend-app-account#1468 was for Account.

A few behaviors change along the way. Errors the sagas used to rethrow, which cancelled the root saga so the page ignored every later action until a reload, are now contained: an account fetch that fails with anything but a 404 shows the error page instead of a spinner that never ends, and a save that fails without field errors resets the form. Opening or closing a field also clears the outcome of the last save, so a field error from a failed save no longer reappears when that field is reopened, and a field opened while another one still shows "Saved" starts clean rather than inheriting that state and losing its drafts to the reset the saga ran 300ms later. An unknown username renders the not-found page in place instead of navigating to /notfound. A rejected photo upload now shows the LMS's message; the alert for it existed but was never fed. After moving a legacy all_users account to per-field privacy, the account and preferences are refetched rather than kept as fetched. The five ProfilePage snapshots are replaced by behavior assertions, and the unused state.userAccount selector, disabledCountries, mock_data.js and the savingEditedBio fixture go without replacement.

Closes #1404.

LLM usage notice

Built with assistance from Claude.

[codecov]

Codecov Report

❌ Patch coverage is 98.90511% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 87.17%. Comparing base (c2669f8) to head (5c773a8).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
src/index.jsx	0.00%	1 Missing ⚠️
src/profile/data/hooks.js	98.43%	1 Missing ⚠️
src/profile/forms/SocialLinks.jsx	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1407      +/-   ##
==========================================
+ Coverage   81.17%   87.17%   +6.00%     
==========================================
  Files          51       47       -4     
  Lines         834      772      -62     
  Branches      240      219      -21     
==========================================
- Hits          677      673       -4     
+ Misses        150       95      -55     
+ Partials        7        4       -3     

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[arbrandes]

Self-review notes, three passes; every finding is fixed and folded into the commit.

First pass: the alert for a rejected photo upload outlived a successful "Remove photo", since it read the save mutation's error and nothing reset it (the delete handler now does). Also two context actions nothing called, a preferences cache merge without the guard the account merge has, no direct test for useDeleteProfilePhoto, a dead formId prop on Certificates, and a platform list duplicated between SocialLinks and derive.js.

Second pass: opening or closing a field left a failed save's saveState and errors in place, so the stale error reappeared when the field was reopened. The reducer now clears both, which made the saga's 300ms reset step a no-op, so the provider keeps a single close timer. The certificates branch of the edit mode had no caller once Certificates stopped being connected, and every field component was subscribing to the certificates query just to feed it.

Third pass: leftovers only. RESET_DRAFTS had no dispatcher, SAVE_FAILURE could never actually merge, useProfileData returned values the page already takes from the form context, and the description gained a sentence on the open/close change.