Align src codebase with latest Ruff ruleset

[Copilot]

This updates src to satisfy the latest ruff check src requirements by addressing each reported error type with targeted refactors. Changes are scoped to lint-driven correctness/style updates without introducing new features.

• Lint-driven cleanups across src

  • Applied safe Ruff autofixes for import ordering, string formatting modernizations, annotation rewrites, and minor simplifications.
  • Removed redundant expressions and dead/no-op statements flagged by Ruff.

• Manual fixes for non-auto-fixable findings

  • Replaced bare open(...) usage with context managers in file-upload helpers.
  • Reworked index-counter loops to enumerate(...) where required.
  • Collapsed nested if blocks into single conditions where semantics were unchanged.
  • Replaced broad except Exception handlers with narrower exception tuples in touched paths.
  • Updated dictionary iteration patterns to use .items() when both key/value are used.

• Behavior-preserving return-path corrections

  • Fixed branches that evaluated values without returning them (e.g., returning xticks directly in fallback paths).

# before
for field in fields:
    if field in record:
        aux[fields[field]] = record[field]

# after
for field, value in fields.items():
    if field in record:
        aux[value] = record[field]

• Fixes Update to match latest ruff version #46

[enryH]

was an actual error...

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Keep handling eigensolver convergence failures

When nx.eigenvector_centrality_numpy fails to converge for a valid 6–149-edge input graph, SciPy raises scipy.sparse.linalg.ArpackNoConvergence, which is neither a NetworkXException nor a ValueError. The previous broad handler allowed get_network to continue rendering with degree-based sizing, but this narrowed tuple now lets that exception abort the entire network visualization; include the documented eigensolver exception in the fallback handling.

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