windows-reactor gaps and hardening

[Kenny Kerr (kennykerr)]

Some improvements based on https://github.com/damyanp/netmon-rs/blob/main/reactor-notes.md

[Copilot]

Pull request overview

This PR hardens windows-reactor based on external field reports by adding a central fault boundary for WinUI callback panics, filling functional gaps (window icon support), and fixing/reproducing correctness issues with new regression tests and samples.

Changes:

• Add a reactor-owned fault boundary (fault) and public App::on_fault hook to catch/report panics from WinUI callback entry points.
• Add window icon support via App::icon + un-stub IAppWindow::SetIcon, plus a sample.
• Fix nested component re-render pruning and add regressions; add animated_canvas unmount teardown + regression.

Reviewed changes

Copilot reviewed 20 out of 21 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
docs/crates/windows-reactor.md	Documents the new fault/panic contract and field-reported friction items.
crates/tools/reactor/src/base.txt	Un-stubs IAppWindow::SetIcon in the bindings filter.
crates/tests/libs/reactor/tests/nested_state_rerender.rs	Regression test for nested component re-rendering from its own use_state.
crates/tests/libs/reactor_selftest/src/bindings.rs	Regenerated selftest bindings to include IAppWindow::SetIcon.
crates/tests/libs/canvas/src/lib.rs	Regression asserting animated_canvas installs an unmount teardown.
crates/tests/libs/canvas/Cargo.toml	Enables windows-canvas reactor feature and adds windows-reactor for the new test.
crates/samples/reactor/samples/examples/on_fault.rs	New sample demonstrating App::on_fault behavior.
crates/samples/reactor/samples/examples/icon.rs	New sample demonstrating App::icon.
crates/libs/reactor/src/reconciler.rs	Seeds forced re-render for state-dirty nested components to avoid pruning bugs.
crates/libs/reactor/src/lib.rs	Adds fault module and exports Fault.
crates/libs/reactor/src/interaction.rs	Wraps callback invocation with the fault boundary.
crates/libs/reactor/src/host.rs	Applies icon/presenter/backdrop best-effort work via fault reporting inside activate.
crates/libs/reactor/src/hooks.rs	Wraps timers/rendering callbacks with the fault boundary.
crates/libs/reactor/src/fault.rs	New central fault boundary (catch, render_scope, report) + unit tests.
crates/libs/reactor/src/engine.rs	Wraps render pass in fault::render_scope.
crates/libs/reactor/src/bindings.rs	Regenerated reactor bindings to include IAppWindow::SetIcon.
crates/libs/reactor/src/backend/winui/mod.rs	Consolidates best-effort COM drops/logging through diag::{warn,dropped}.
crates/libs/reactor/src/backend/winui/diag.rs	Introduces unified debug-only warn/drop helpers with #[track_caller].
crates/libs/reactor/src/app.rs	Adds App::icon + file validation and App::on_fault handler installation.
crates/libs/canvas/src/reactor.rs	Adds animated_canvas unmount teardown to break a reference cycle and stop leaks.