feat: add Inertia Precognition support

[DominusKelvin]

Summary

• add Precognition request helpers, response headers, 204 success handling, and 422 JSON error handling to inertia-sails
• humanize Sails/Anchor/RTTC validation errors so Precognition and normal Inertia validation share friendlier messages
• wire the Mellow and Ascent templates for Precognition success responses, live forgot-password validation, and polished input error states
• replace forgot-password controller unit tests with Sounding functional tests where template coverage is added

Validation

• npm --workspace inertia-sails test
• npm --workspace rsbuild-plugin-inertia test
• node --check templates/ascent-vue/api/controllers/auth/forgot-password.js
• node --check templates/mellow-react/api/controllers/auth/forgot-password.js
• node --check templates/mellow-vue/api/controllers/auth/forgot-password.js
• manually verified Mellow Vue forgot-password Precognition returns Please enter a valid email address

Notes

• templates now assume the upcoming inertia-sails release that includes the Precognition helpers

Closes #197