[Gulliby]

Requested by gulliby

Before

A key assigned twice in .env silently uses the last value, and envguard did not report it.

After

envguard --duplicates also lists keys that .env assigns more than once. They are warnings (errors with --strict); the template file is not checked. Without the option nothing changes.

With .env.example A= and .env A=1, B=2, A=3:

$ envguard --duplicates
Success: required environment keys are present and non-empty.
Extra keys (warnings): B
Duplicate keys (warnings): A

It exits 0; with --strict the exit code is 1. --json adds a last "duplicate" field and --github adds one annotation per key.

How

• src/parse.ts: new findDuplicateKeys, sharing the assignment parsing with parseEnv.
• src/format.ts: optional duplicate in createReport and Report, and the human and GitHub output.
• src/cli.ts: the --duplicates option and help line.
• README.md: options row and a "Duplicate keys" section.
• tests/duplicates.test.ts: 18 new tests; existing tests are unchanged.