Wire config.resilience to translator

[jserv]

The resilience config (circuit breaker thresholds, HTTP timeouts, retry counts, backoff delays) was defined in ResilienceConfig but never wired to the translator -- all three OnceLock singletons used hardcoded defaults. Similarly, fallback_to_passthrough existed in config but was never checked; translation errors unconditionally returned the original text.

Fix both by:

• Adding init_resilience() to seed OnceLock singletons (circuit breaker, rate limiter, HTTP client) with user config before the first request
• Threading &ResilienceConfig through translate_with_chunking, translate_chunks, and google_translate_with_retry_config
• Extracting build_http_client() as single source of truth for the reqwest::Client builder (eliminates duplicated chain)
• Checking config.resilience.fallback_to_passthrough in main.rs error handler: true (default) returns original text, false exits with status 1
• Guaranteeing at least one translation attempt even if max_retries is 0 (prevents u32 wrapping and zero-attempt failure)

[codecov]

Codecov Report

❌ Patch coverage is 46.42857% with 15 lines in your changes missing coverage. Please review.
✅ Project coverage is 65.16%. Comparing base (ab23e59) to head (cbc848f).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
src/translator.rs	46.42%	15 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #11      +/-   ##
==========================================
- Coverage   65.37%   65.16%   -0.22%     
==========================================
  Files          11       11              
  Lines         774      775       +1     
==========================================
- Hits          506      505       -1     
- Misses        268      270       +2     

Flag	Coverage Δ
unittests	65.16% <46.42%> (-0.22%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
src/translator.rs	45.67% <46.42%> (-0.23%)	⬇️

... and 1 file with indirect coverage changes

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