Libsreg TrustEnv config

[mejroslav]

Summary

LibsRegLibraryProvider hardcodes TrustEnv = True when creating the aiohttp.ClientSession for periodic library pulls. This value should be configurable via the [general] config section.

Problem

In asab/library/providers/libsreg.py, the HTTP client used to download library archives always trusts environment variables for proxy/SSL settings:

# TODO: Read this for `[general]` config
self.TrustEnv = True

Used later as:

async with aiohttp.ClientSession(connector=connector, trust_env=self.TrustEnv) as session:
    async with session.get(url, headers=headers) as response:
        ...

When trust_env=True, aiohttp reads proxy settings from environment variables (HTTP_PROXY, HTTPS_PROXY, NO_PROXY, etc.). This is useful in corporate/restricted networks, but it cannot be disabled or overridden without code changes.

Expected behavior

TrustEnv should be read from configuration, following the same pattern as other global settings in [general] (e.g. tick_period, pidfile).

Suggested config:

[general]
trust_env=true

• Default: true (preserve current behavior)
• When false: aiohttp ignores proxy-related environment variables

Proposed implementation

• Add trust_env to [general] defaults in asab/config.py (default: true)

• Read the value in LibsRegLibraryProvider.init():

  self.TrustEnv = asab.Config.getboolean("general", "trust_env", fallback=True)

• Document the option in docs/reference/services/library.md (libsreg section)

• Add to etc/sample.conf (optional, commented)