fix(service): preserve explicit env_file and stop implicit .env injection

[1312e]

Summary

• stop auto-injecting .env into env_file for parsed compose services/applications
• preserve only explicitly defined env_file entries from user compose
• refactor env_file normalization into a shared helper for both parser flows
• add regression coverage for env_file normalization + structure guards

Why

Docker Compose semantics treat .env as interpolation input, not implicit runtime env injection for every service. Auto-injecting .env can leak variables into containers that never opted in.

Scope

This PR is intentionally minimal and only contains #7655-related parser/test changes.

Tests

• php -l bootstrap/helpers/parsers.php
• php -l tests/Unit/ComposeEnvFileSemanticsTest.php
• tests/Unit/ComposeEnvFileSemanticsTest.php covers:
  • normalization + trim + dedupe behavior
  • missing env_file behavior
  • invalid non-string filtering
  • helper usage in both parser flows + no implicit ->push('.env')

Docs

N/A - internal parser behavior change; no user-facing service template/docs page changes.

Bounty

/claim #7655

[1312e]

Validation run (local):

php -l bootstrap/helpers/parsers.php
# No syntax errors detected in bootstrap/helpers/parsers.php

php -l tests/Unit/ComposeEnvFileSemanticsTest.php
# No syntax errors detected in tests/Unit/ComposeEnvFileSemanticsTest.php

Regression guard added in tests/Unit/ComposeEnvFileSemanticsTest.php to ensure implicit ->push('.env') is not reintroduced in either parser path.

[1312e]

@ShadowArcanist could you please take a look when you have time? This PR is scoped only to remove implicit .env runtime injection and keep explicit env_file behavior for compose semantics.

[Cinzya]

@1312e bountys require a video demo, please provide. Also you aren't following our Contribution Guidelines.