fix(deps): bump better-auth to 1.4.9

[agent-horton]

Summary

• Fixes Dependabot alert chore: Fix capacitor driver changeset #593 by updating better-auth in examples/tanstack-db-web-starter from 1.4.3 to 1.4.9.
• Updates pnpm-lock.yaml for the new better-auth release and transitive dependency resolution.
• Applies the lint autofix needed for the example's sst.config.ts.

Validation

• pnpm --config.engine-strict=false --filter @electric-sql/client run build
• pnpm --config.engine-strict=false --filter ./examples/tanstack-db-web-starter run test
• pnpm --config.engine-strict=false --filter ./examples/tanstack-db-web-starter run build
• pnpm --config.engine-strict=false --filter ./examples/tanstack-db-web-starter run lint:check

[github-actions]

Electric Agents Desktop Builds

Build artifacts for commit c1991fe.

Platform	Status	Artifact
macOS Apple Silicon	Passed	DMG
macOS Intel	Passed	DMG
Windows x64	Passed	Installer
Linux x64	Passed	AppImage / deb

Workflow run

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 58.99%. Comparing base (16c8339) to head (c1991fe).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #4619       +/-   ##
===========================================
- Coverage   71.68%   58.99%   -12.69%     
===========================================
  Files          84      385      +301     
  Lines       10155    42677    +32522     
  Branches     3252    12221     +8969     
===========================================
+ Hits         7280    25179    +17899     
- Misses       2855    17422    +14567     
- Partials       20       76       +56     

Flag	Coverage Δ
packages/agents	72.62% <ø> (ø)
packages/agents-mcp	77.70% <ø> (?)
packages/agents-mobile	80.67% <ø> (?)
packages/agents-runtime	82.73% <ø> (?)
packages/agents-server	75.29% <ø> (-0.03%)	⬇️
packages/agents-server-ui	7.54% <ø> (?)
packages/electric-ax	47.62% <ø> (ø)
packages/experimental	87.73% <ø> (?)
packages/react-hooks	86.48% <ø> (?)
packages/start	82.83% <ø> (?)
packages/typescript-client	91.71% <ø> (?)
packages/y-electric	56.05% <ø> (?)
typescript	58.99% <ø> (-12.69%)	⬇️
unit-tests	58.99% <ø> (-12.69%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[github-actions]

Electric Agents Mobile Build

Local mobile checks ran for commit c1991fe.

The EAS Android preview build was skipped because the mobile-eas-build label is not present.
Add the mobile-eas-build label to this PR to produce an installable preview build.

Workflow run