feat: support admin password file env

[bxn-dev]

Adds file-based admin password support for the IDM admin user.

Supported env vars:

• ADMIN_PASSWORD_FILE for opencloud init
• IDM_ADMIN_PASSWORD_FILE for opencloud init
• IDM_ADMIN_PASSWORD_FILE for the IDM service config parser

The file content is read and trailing \n / \r\n is trimmed. Supplying both a direct password env var and a password file env
var returns a config error.

Related Issue

• Fixes Add support for IDM_ADMIN_PASSWORD_FILE #2982

Motivation and Context

This allows deployments to provide the IDM admin password via Docker secrets or mounted secret files instead of exposing the
password directly through environment variables.

How Has This Been Tested?

• test environment: local checkout on branch feat/2982_idm_admin_passwort_file
• test case 1: helper tests for no file env, file env, trailing newline trimming, direct-value conflict, and missing file
• test case 2: IDM parser test for IDM_ADMIN_PASSWORD_FILE
• test case 3:

go test ./pkg/config ./opencloud/pkg/command ./services/idm/pkg/...

Screenshots (if appropriate):

N/A

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Technical debt
• Tests only (no source changes)

Checklist:

• Code changes
• Unit tests added
• Acceptance tests added
• Documentation added

[codacy-production]

Up to standards ✅

🟢 Issues 0 issues

Results:
0 new issues

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🟢 Metrics 2 duplication

Metric	Results
Duplication	2

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