# DEVX-164: Increase HTTP 500 retry count and backoff for docker push

## Problem
The HTTP 500 retry logic (DEVX-162, DEVX-163) works correctly — 3 retry
attempts are made. But all 3 attempts fail because the Gitea registry's
"offset mismatch" race condition needs more than ~15s to recover. The
current backoff is 5s-20s with 3 attempts (total ~15s of waiting).

## Approach
Increase retry count from 3 to 5 and backoff from 5-20s to 10-60s,
giving the registry up to ~2 minutes to recover. Add visible logging
between retry attempts so the CI logs show the retry happening.

REQ-1: Increase retry count from 3 to 5
REQ-2: Increase backoff from 5-20s to 10-60s exponential
REQ-3: Add visible logging between retry attempts (click.echo)
REQ-4: All tests pass with 100% coverage

## Test Plan
- Unit tests verify retry count and backoff parameters
- Unit tests verify logging output on retry
- Manual: trigger build-images workflow and verify retries visible in logs

## Deploy Plan
- Merge to master

## Rollback Plan
- Revert the merge commit

## Acceptance Criteria
- [x] REQ-1: Increase retry count from 3 to 5
- [x] REQ-2: Increase backoff from 5-20s to 10-60s exponential
- [x] REQ-3: Add visible logging between retry attempts (click.echo)
- [x] REQ-4: All tests pass with 100% coverage