fix(hydration): make chart-repo sync-app timeout configurable, default 30s

[aamsellem]

Summary

The TaskForApiStep HTTP client had a hardcoded 3 second timeout on its call to chart-repo's /chart-repo/api/v2/dcr/sync-app endpoint. That endpoint runs the full hydration pipeline synchronously (download chart → render → image analysis → DB update). On a first-time install of a new chart the call typically takes ~4 seconds end-to-end — and longer when chart-repo is concurrently processing other sources in the background.

This causes new charts (especially from third-party market sources) to silently fail to install, even though chart-repo itself completes the work successfully a moment after the market client gives up.

Symptoms (observed in production)

market pod:
```
TaskForApiStep - Request failed in 3.000439s for user=…, source=…, app=14fdab3c:
Post "http://chart-repo-service:82/chart-repo/api/v2/dcr/sync-app\":
context deadline exceeded (Client.Timeout exceeded while awaiting headers)
Step 1 (TaskForApiStep) failed for task: …, moving to render failed list
Removed app 14fdab3c from pending list for user: …, source: …
```

chart-repo pod (same task, ~1 second later):
```
HYDRATION STEP 5/5 COMPLETED: Database and Cache Update
HYDRATION TASK COMPLETED
App 14fdab3c rendering completed successfully
```

The result: hydration succeeded server-side but the orchestrator dropped the app, and the user has to wait for cache cleanup or manually purge Redis to retry.

Changes

• bump default timeout from 3 * time.Second to 30 * time.Second
• allow operators to override via the MARKET_CHART_REPO_TIMEOUT_SECONDS environment variable
• log a warning (and fall back to default) if the env var value is missing/invalid
• expand the comment block to document why this timeout matters

Why 30s

Empirically, chart-repo sync-app returns within 4–6 seconds for new charts on a typical Olares device. 30 seconds gives a comfortable margin for cold starts, slow disks, or transient contention with the background hydration of large official catalogs (~200 apps). It is still short enough to surface a real failure quickly.

Test plan

• Install an app from a third-party market source for the first time and verify hydration completes through TaskForApiStep without hitting the deadline.
• Set MARKET_CHART_REPO_TIMEOUT_SECONDS=60 and confirm the configured value is used.
• Set MARKET_CHART_REPO_TIMEOUT_SECONDS=abc and confirm a warning is logged and the default (30s) is used.