feat(debug): call graph, state events, and breakpoint improvements

[cristipufu]

Summary

• AST-based call graph builder (graph_builder.py): parses user code from an entrypoint function, builds a UiPathRuntimeGraph with file:line node IDs that double as breakpoint locations
• State events during execution: emits UiPathRuntimeStateEvent for every call-graph function entry (even without breakpoints), so the debug bridge can visualise execution flow through graph nodes
• OTEL context propagation: copies contextvars to the background trace thread so @traced decorator spans are properly linked to the parent trace
• Breakpoint reliability fixes:
  • Node IDs point to the first executable body line (skipping docstrings) instead of the def line, preventing false breakpoint hits during module imports
  • <module> frame line events are skipped in the trace callback
  • Per-frame deduplication prevents multiline expressions (e.g. return Foo(arg=bar(...))) from triggering the same breakpoint twice due to bytecode line bouncing

Test plan

• 11 tests for AST call graph builder (multi-file, async, relative imports, depth limits, etc.)
• E2E tests for state events: with/without breakpoints, through decorator wrappers, external function exclusion
• Test for multiline expression breakpoint deduplication
• All 1968 existing tests pass
• ruff check, ruff format, mypy all clean

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