docs: update skills for Better Auth 1.5

[jschill]

Summary

• verifyPassword is server-only: Corrected the emailAndPassword skill to remove the incorrect authClient.verifyPassword() example; now shows only auth.api.verifyPassword(...) with a clear server-only callout
• CLI command updates: Updated Quick Start steps in emailAndPassword, organization, and twoFactor skills to use npx auth migrate (the new canonical command), with the old @better-auth/cli form noted as a deprecated alias
• Breaking changes documented: permission → permissions rename in organization dynamic access control, sendChangeEmailVerification → sendChangeEmailConfirmation rename, after-DB-hooks now run post-transaction
• New 1.5 features documented: Secret rotation via secrets array, hardened rate-limit defaults, IPv6 subnet config, verification token storage, @better-auth/api-key extraction, @better-auth/oauth-provider, standalone adapter packages (@better-auth/drizzle-adapter, @better-auth/prisma-adapter, @better-auth/kysely-adapter, @better-auth/mongo-adapter)
• Expanded plugin and adapter tables in create-auth and best-practices skills with new 1.5 packages and options

Files changed

File	Status
better-auth/best-practices/SKILL.md	Updated
better-auth/create-auth/SKILL.md	Updated
better-auth/emailAndPassword/SKILL.md	Updated
better-auth/organization/SKILL.md	Updated
better-auth/twoFactor/SKILL.md	Updated
security/SKILL.MD	Updated