fix(sentry): drop offline-device gaierror events in before_send

[vpetersson]

Issues Fixed

• Fixes Sentry noise: offline devices report gaierror per network call, 253/day (Sentry ANTHIAS-3G) #3126 (Sentry ANTHIAS-3G)

Description

A device without working DNS (offline, captive portal, upstream outage) reported gaierror: [Errno -5] No address associated with hostname to Sentry on every attempted external call — 253 events in under a day from a single pi3-64. Every one of those events is the asyncio Future exception was never retrieved error log inside uvicorn, with no stack trace, so there's nothing actionable in them; being offline is a routine operating state for a signage device.

This adds socket.gaierror to the before_send transient-drop list, chain-checked like the redis errors so requests-wrapped resolution failures (urllib3 NameResolutionError → requests.ConnectionError) are dropped too. Same policy precedent as the redis blips (ANTHIAS-M/K/H/J), client disconnects (ANTHIAS-N), and AuthSettingsError (ANTHIAS-3D).

Follow-up worth tracking separately: something in the ASGI process abandons an asyncio future that resolves with the DNS error (that's how these surface as "Future exception was never retrieved"). Pinning down the creator needs a live offline-device repro; this PR stops the fleet-wide quota burn regardless of the source.

Validation on real hardware

Exercised in the real server container on the x86 testbed: _sentry_before_send with a socket.gaierror returned None (event dropped), while a real ValueError was kept — confirming the filter drops offline noise without swallowing genuine bugs. Server-side and arch-independent.

Checklist

• I have performed a self-review of my own code.
• New and existing unit tests pass locally and on CI with my changes.
• I have done an end-to-end test for Raspberry Pi devices.
• I have tested my changes for x86 devices.
• I added a documentation for the changes I have made (when necessary).

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR reduces Sentry noise for offline/captive-portal devices by dropping DNS-resolution failures (socket.gaierror, including when wrapped by higher-level HTTP exceptions) in the Sentry before_send hook.

Changes:

• Add socket.gaierror to the transient-drop list in _sentry_before_send, using the existing exception-chain walk.
• Add unit tests ensuring raw and wrapped gaierror events are dropped.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/anthias_server/django_project/settings.py	Drops socket.gaierror (and chained/wrapped instances) in Sentry before_send; updates docstring rationale.
tests/test_sentry.py	Adds regression tests verifying gaierror and wrapped gaierror events are filtered out.

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.