docs: polish the 3.2.2 release notes and the pages they link to

[fgmacedo]

Why

Since v3.2.1, seven PRs each appended a section to docs/releases/3.2.2.md. A read-only audit of git log v3.2.1..origin/main found 8 gaps: a missing entry for #650, undocumented exception and event-listing changes, uncredited contributors, and no upgrade checklist for a patch release that changes behavior.

What changes

• The 3.2.2 notes open with a summary and a "Behavior changes to check when upgrading" list. It has 14 items, each one line long and linking to its section, and every item was probed against v3.2.1 and main.
• The fixes are grouped by theme: event declarations and queues; nested state bodies and inheritance; diagrams and Sphinx; documentation. Every entry cites its issue and its PR, with credits for @rastagan-git (fix: resolve Sphinx diagram zoom links relative to the current page #650), @JMerrill-Fairness (fix: keep event order, measure delays on the monotonic clock, cancel by marking #665), @MartinBernstorff (bug: compound states nested in parallel states are not marked as active #651/fix: mark compound states nested in parallel states as active #652) and @chiliec (fix: honor Event(internal=True) when the event is triggered #663, merged as fix: honor Event(internal=True) and give internal events from outside a step the external contract #668).
• Entries that were missing or wrong are added or corrected:
  • fix: resolve Sphinx diagram zoom links relative to the current page #650 (relative Sphinx zoom links).
  • GraphvizError replaces pydot's AssertionError / FileNotFoundError, and the entry says what to catch now.
  • A nested-body method named like an event is rejected.
  • Events queued after a top-level final state are dropped.
  • The macrostep ordering change.
  • raise_() and send(..., internal=True) from outside a step.
  • raise_() on an event declared with a delay.
  • TriggerData.execution_time is on the monotonic clock.
• The two overlapping delay/internal sections become one, and the three fix: keep event order, measure delays on the monotonic clock, cancel by marking #665 sections become one. Beacons is no longer defined twice.
• events.md documents Event(delay=..., internal=...) and nested-body declarations. statechart.md covers declared delays. processing_model.md states that the queue is discarded on termination. diagram.md gains a diagram-graphviz-errors anchor, what to catch, and the relative zoom link.

Refs #643, #644, #646, #649, #651, #653, #654, #655

Evidence

$ timeout 120 uv run pytest docs/releases/3.2.2.md docs/events.md docs/statechart.md docs/processing_model.md docs/diagram.md --no-cov -q
5 passed
$ timeout 180 uv run pytest -n 4
2664 passed, 25 skipped, 44 xfailed
$ uv run sphinx-build -q docs docs/_build/html 2>&1 | grep -ci warning   # main vs branch
48 / 48   (none in the changed files)

Behavior claims were checked by running the same probe scripts against git archive v3.2.1 statemachine (via PYTHONPATH) and against this branch. For example, raise_() on a StateMachine from outside: None before, TransitionNotAllowed now. Four rounds of adversarial review (the fourth after the rebase) read the notes as a user upgrading from 3.2.1. The fourth found one missing upgrade item (send(..., delay=...) on an event declared internal=True now raises InvalidDefinition), now listed, and the delay+internal doctest now checks the exception message (-IGNORE_EXCEPTION_DETAIL).

Not verified

• Rebased onto fix: name the event in the delayed+internal error and let send(delay=0) override #683, fix: keep FileNotFoundError catching a missing Graphviz dot #680 and fix: answer callers of events dropped when the machine terminates #685 (fixes for Event(..., delay=..., internal=True) error shows the placeholder id instead of the attribute name #679 and Async: awaiting send() of an event dropped after reaching a final state hangs forever #678, and GraphvizNotFoundError); the notes describe their final behavior, checked with probes on sync and async, but the async drop scenarios were exercised only with asyncio.gather in a single event loop.
• {class} roles for InvalidDefinition and StateMachineError render unlinked, because neither class is autodoc'd. This pattern predates this PR.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (38968c1) to head (feafad4).

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #682   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           53        53           
  Lines         5816      5816           
  Branches       926       926           
=========================================
  Hits          5816      5816           

Flag	Coverage Δ
unittests	100.00% <ø> (ø)

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

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud