feat: add remember password function

[bittoby]

Related Issue

Closes #1316

Description

Adds secure "Remember Me" credential storage for the login page using Electron's built-in safeStorage API, which encrypts credentials via OS-level keychain (macOS Keychain, Windows DPAPI, Linux Secret Service). No new dependencies required.

What it does:

• Encrypts and persists email/password credentials locally at ~/.eigent/saved_credentials.enc (file permissions 0o600)
• Auto-fills the most recently used account on login page load
• Shows a saved accounts dropdown (with masked emails) when focusing the email field, allowing quick account switching
• Each saved account can be individually removed from the dropdown
• "Remember Me" checkbox controls whether credentials are saved or cleared after successful login

Files changed:

• electron/main/index.ts — 3 IPC handlers (credentials-save, credentials-load, credentials-remove) using safeStorage.encryptString() / decryptString()
• electron/preload/index.ts — Exposed credential APIs to renderer via electronAPI bridge
• src/types/electron.d.ts — TypeScript declarations for new credential methods
• src/pages/Login.tsx — Remember Me checkbox, saved accounts dropdown with outside-click dismiss, auto-fill on mount
• 11 i18n locale files — Added remember-me, saved-accounts, remove-account keys (en, zh-Hans, zh-Hant, ja, ko, de, fr, es, it, ru, ar)

Testing Evidence (REQUIRED)

login.mp4

• I have included human-verified testing evidence in this PR.
• This PR includes frontend/UI changes, and I attached screenshot(s) or screen recording(s).
• No frontend/UI changes in this PR.

What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

Contribution Guidelines Acknowledgement

• I have read and agree to the Eigent Contribution Guideline

[bittoby]

@Pakchoioioi @Wendong-Fan Could you please review the PR?
thank you

[Wendong-Fan]

thanks @bittoby ! could @4pmtong and @fengju0213 help reviewing this feature?

[bittoby]

@Wendong-Fan @4pmtong @fengju0213 I'd really appreciate your feedback!
thank you

[nitpicker55555]

This PR has several serious issues. A pure function is wrapped in useMemo even though it does not depend on any state and should be defined outside the component. Returning a function from useMemo with an empty dependency array is meaningless and looks like AI-driven over-optimization. The implementation stores plaintext passwords instead of persisting the existing auth token via setAuth, which indicates the current authentication flow was not properly reviewed. There is also a redundant map in credentials-load where the input and output shapes are identical, making it unnecessary code. In addition, credentialsLoad() has no error handling and lacks a catch on the promise.

Considering the extent of these problems, iterating through review cycles would likely cost more effort than rewriting it. I suggest closing this PR and submitting a clean one instead. @Wendong-Fan @4pmtong

[bittoby]

@nitpicker55555 please don't close this PR. I will update in this PR

[bittoby]

@nitpicker55555 I updated to follow your feedback.

What i have changed:

• Password storage removed - the implementation now persists the auth token (token, username, user_id) returned by the login API, not the user's password. Selecting a saved account calls setAuth directly and navigates without re-entering credentials.
• useMemo misuse removed - maskEmail is now a plain module-level function outside the component.
• Redundant .map() removed - credentials-load returns the accounts array directly.
• Error handling added - credentialsLoad is now wrapped in try/catch.
• Runtime bug fixed - the account filter was rejecting all saved entries because user_id from the API is a string at runtime, not a number. The filter now only validates email and token, which is sufficient.

[fengju0213]

@nitpicker55555 I updated to follow your feedback.

What i have changed:

• Password storage removed - the implementation now persists the auth token (token, username, user_id) returned by the login API, not the user's password. Selecting a saved account calls setAuth directly and navigates without re-entering credentials.
• useMemo misuse removed - maskEmail is now a plain module-level function outside the component.
• Redundant .map() removed - credentials-load returns the accounts array directly.
• Error handling added - credentialsLoad is now wrapped in try/catch.
• Runtime bug fixed - the account filter was rejecting all saved entries because user_id from the API is a string at runtime, not a number. The filter now only validates email and token, which is sufficient.

thanks @bittoby will review it asap

[fengju0213]

thanks @bittoby overall its good，I'm wondering if automatic autofill is sufficient, and automatic login isn't necessary, because there might be other operations on this login page later, such as changing the password, etc.
cc @Pakchoioioi

[bittoby]

Thanks for your feedback @bytecii . I will check again

[bittoby]

@bytecii I have updated all to follow your feedback. please review again.
thank you

[bittoby]

@Wendong-Fan @bytecii please review again. I fixed all. Thanks

[bittoby]

@fengju0213 It passed all tests