fix: write a valid care_fe/.env.local so the frontend dev server starts

[amjithtitus09]

Problem

After care create, care run can't bring up the frontend:

1. care_fe's dev server fails env validation. create copied care_fe's .example.env into care_fe/.env.local. That template leaves most keys blank (REACT_GITHUB_URL=, REACT_MAIN_LOGO=, …). Vite loads them as "", and care_fe's scripts/validate-env.ts rejects them because zod's .optional() only accepts a missing key. Vite aborts with 17 validation errors.
2. With the ABDM frontend plug selected, the app would crash on load. REACT_ENABLED_APPS was written as care_abdm_fe@localhost:5173. care_fe's care.config.ts expects org/repo@host/path/to/remoteEntry.js and throws Invalid plug configuration: care_abdm_fe. Expected 'org/repo@url'. while the module loads. Adding just the org isn't enough: care_fe merges this entry's URL over the plugin config the CLI registers in the backend, and @localhost:5173 resolves to http://localhost:5173/ instead of remoteEntry.js.

Changes

• create writes only the CLI's own keys to care_fe/.env.local (REACT_CARE_API_URL, REACT_ENABLED_APPS, plus any plug env) and no longer copies .example.env. The defaults already come from care_fe/.env, and care_fe's README only asks for REACT_CARE_API_URL in .env.local.
• A new remoteEntryUrl() helper supplies the URL for both the registered plugin config and REACT_ENABLED_APPS, which is now org/repo@host/assets/remoteEntry.js.
• plugs.json: enabledApp for care_abdm_fe is now 10bedicu/care_abdm_fe. types.ts documents the org/repo format.

Testing

• npm run typecheck and npm run build pass. The built dist/cli.js no longer references .example.env.
• Ran create --skip-install against a scratch setup that had care_fe's real .example.env in place (Docker runtime, care_abdm_fe selected). The generated care_fe/.env.local is exactly:

  REACT_CARE_API_URL=http://127.0.0.1:9000
  REACT_ENABLED_APPS=10bedicu/care_abdm_fe@localhost:5173/assets/remoteEntry.js
  

• With that file, care_fe (develop) starts, the landing page renders, and the ABDM plugin's remoteEntry.js and manifest load from :5173.
• Ran care_fe's careApps parsing from care.config.ts on three values. The old value throws, org-only gives http://localhost:5173/, and the new value gives the remoteEntry.js URL.
• Not done: a clean-slate create → run from the packed tarball in an empty directory.

Notes for reviewers

• Setups created with 0.2.0 or 0.2.1 aren't repaired by this PR. Re-running create only rewrites the CLI's own keys, so the blank template lines stay. Workaround: delete care_fe/.env.local, then re-run care create --skip-install. A follow-up could have create drop blank KEY= lines from an existing file.
• The completion message still says cd <dir> && care run. That doesn't work after npx @ohcn/care create, because npx doesn't put care on the PATH. Those users need npx @ohcn/care run <dir>. This is also left for a follow-up.