Exceptions cleanup: narrow catches, remove hidden RNG resets, and make provenance timestamps UTC-aware

[Copilot]

This PR addresses exception hygiene and reproducibility gaps: broad except: blocks were masking failures, two statistics functions were mutating global RNG state via hardcoded np.random.seed(42), and provenance timestamps used deprecated naive UTC creation.

• Exception handling hardening

  • Replaced bare except: with targeted exception types across affected runtime modules:
    • py3plex/algorithms/robustness_testing.py
    • py3plex/algorithms/statistical_report.py
    • py3plex/uncertainty/community_ensemble.py
    • py3plex/algebra/paths.py
    • py3plex/meta/utils.py
    • py3plex/visualization/multilayer.py
  • This preserves fallback behavior while avoiding swallowing KeyboardInterrupt/SystemExit.

• RNG behavior in multilayer statistics

  • Removed internal hardcoded seeding from:
    • interdependence(...)
    • resilience(...)
  • Added optional seed parameters and switched to local generators (np.random.default_rng(seed)), so callers control determinism without global RNG side effects.

• Timezone-aware provenance timestamp

  • Replaced deprecated naive UTC timestamp generation in py3plex/meta/utils.py with timezone-aware UTC output normalized to Z.

• Focused coverage updates

  • Extended tests/test_multilayer_statistics.py with deterministic seed behavior checks for interdependence and resilience.
  • Added tests/test_meta_utils.py to assert timezone-aware timestamp_utc formatting.

# Before: hidden global RNG mutation
# np.random.seed(42)
# n1, n2 = np.random.choice(all_nodes, size=2, replace=False)

# After: caller-controlled local RNG
rng = np.random.default_rng(seed)
n1, n2 = rng.choice(all_nodes, size=2, replace=False)