Allow importing environment variables via file upload or paste - Codex Web

Description

In Codex Web, adding secrets/environment variables one by one is tedious and error-prone. For projects with many variables (e.g., .env files), this becomes frustrating and slows setup significantly.

It would be much better to support bulk input, either by:

• Drag & drop of a .env file
• Uploading a file
• Pasting raw environment variable text

Problem / Motivation

Many projects already define environment variables in a standard .env format, for example:

DATABASE_URL=postgres://...
REDIS_URL=redis://...
JWT_SECRET=superlongsecret
STRIPE_API_KEY=sk_live_...

Re-entering these manually in the UI:

• Is time-consuming
• Increases risk of typos
• Discourages proper secret hygiene
• Makes onboarding painful for larger projects

This is especially frustrating when migrating an existing project into Codex Web.

Expected Behavior

Users should be able to:

• Upload a .env file
• Drag & drop a file into the secrets UI
• Or paste multiple lines of KEY=VALUE pairs

The system should:

• Parse valid KEY=VALUE lines
• Ignore comments (# comment)
• Validate key format
• Show a preview before saving
• Prevent accidental overwrites (warn if a key already exists)

Acceptance Criteria

• Multiple secrets can be added in one action
• Standard .env format is supported
• Invalid lines are clearly reported
• Users can confirm before applying changes
• Existing secrets are not silently overwritten

Nice-to-haves

• Option to merge vs replace existing variables
• Highlight duplicates before confirming
• Basic format validation (e.g., invalid key names)