Add dedicated sign-in screen for returning users

[Copilot]

Resolved TODO in welcome screen: both "Sign In" and "Create Account" buttons were routing to the same account creation screen, forcing returning users through the signup flow.

Changes

• New screen: app/(auth)/sign-in.tsx - dedicated authentication interface with email/password inputs, validation, and loading states
• Welcome screen: "Sign In" button now routes to /(auth)/sign-in instead of /account
• Auth layout: registered sign-in screen in navigation stack
• Cross-navigation: added bidirectional links between sign-in and account creation screens

Implementation

// app/(auth)/welcome.tsx
<Button
  label='Sign In'
  theme='secondary'
  onPress={() => {
    router.push('/(auth)/sign-in');  // Previously: router.push('/account')
  }}
/>

Sign-in screen integrates with existing AuthContext.signIn() method, supports both Supabase and demo auth modes, includes form validation and error handling. All changes use established theme system and component patterns.

User flow: Welcome → Sign In → Main App (returning users) | Welcome → Create Account → Main App (new users)

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• cdp.expo.dev
  • Triggering command: /usr/local/bin/node node /home/REDACTED/.npm/_npx/249ca9fcd30c476a/node_modules/.bin/expo start (dns block)
  • Triggering command: /usr/local/bin/node node /home/REDACTED/.npm/_npx/249ca9fcd30c476a/node_modules/.bin/expo start --web (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

Work on TODO: Create dedicated sign in screen or use account screen (from app/(auth)/welcome.tsx)

Created from VS Code via the GitHub Pull Request extension.

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[gitguardian]

⚠️ GitGuardian has uncovered 2 secrets following the scan of your pull request.

Please consider investigating the findings and remediating the incidents. Failure to do so may lead to compromising the associated services or software components.

🔎 Detected hardcoded secrets in your pull request

GitGuardian id	GitGuardian status	Secret	Commit	Filename
26683181	Triggered	Generic Password	c1579cc	scripts/create-test-accounts.js	View secret
26683182	Triggered	Generic Password	c1579cc	scripts/create-test-accounts.js	View secret

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