fix(reactive): bound self-triggered effect re-runs instead of recursing - #186

Summary

Fixes #166 (High).

effect(() => { count.value = count.value + 1 }) re-entered its own observer synchronously (outside a batch, scheduleObserver invokes observers directly), recursing until RangeError: Maximum call stack size exceeded. Wrapping in batch() didn't help since the re-write happens during flush when batchDepth is 0.

Fix

The effect observer gets a re-entrancy guard (per-effect isRunning flag). A self-trigger while running sets reRunRequested and returns; the outer invocation drains re-runs in a bounded do/while loop (MAX_SYNC_RERUNS = 100, Vue-style):

• Effects that settle (e.g. if (count.value < 5) count.value++) converge silently — final value 5, no warning.
• True cycles stop after the bound and log cyclic effect update detected instead of crashing the tab.
• Mutually-recursive effects are covered too: nesting depth stays bounded because the inner trigger only sets a flag.

Dispose-during-run semantics are preserved (cleanup still runs via the finally path).

Verification

• Three new tests: unconditional self-write (no throw + warning), settling self-write (converges, no warning), self-write inside batch().
• Full suite: 2989 pass / 0 fail. tsc --noEmit clean.

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