fix(run): surface --env-from-file parse errors instead of dropping the environment

[htoyoda18]

What I did
getEnvironment in cmd/compose/run.go silently returned (nil, nil) whenever
dotenv.ParseWithLookup failed to parse an --env-from-file (e.g. a
required-variable reference like ${VAR:?message} that can't resolve). Because
the error was swallowed, runRun treated the call as successful and the
container started with an empty environment — including variables passed
via -e — with no error shown to the user.

This PR:

• returns the parse error (wrapped with the file name) instead of discarding it
• closes the file handle opened by os.Open, which was previously never closed
• adds cmd/compose/run_test.go (no unit tests existed for run.go before), covering: e/-env-from-file merge precedence, a missing file, and a malformed file — the last case reproduces the original bug and would have failed before this fix

No behavior change for the success path; only the error path changes from
"silently continue with an empty environment" to "return an error".

Related issue

N/A

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