docs(code-runtime-python): drop the placebo dispose test and finish the remaining doc drift

The review showed the added dispose case was a placebo (dispose in the same
tick as run means SIGTERM hits the group before the program body runs; the
group-emptied arm is already deterministically covered by the same-group
survivor case, which this removes the v8 ignore for). The test is deleted; the
stale silently-discards comment in the boundary test now says rejects; the
README Known Limitations gains the late-log-frame-drop and host-side
binding-value-memory entries. Pairing re-recorded.

packages/code-runtime/code-runtime-python/tests/runtime.spec.ts

@@ -110,9 +110,9 @@ describe('PythonCodeRuntime — seam descriptors and misuse', () => {
     // bytes, so a payload occupies at most `cap + envelope` on the wire; the
     // bound is `parse-cap - envelope`, not `(ceiling - envelope) / 6` (that
     // divided in escape expansion the charge already counts). The receive path
-    // drops raw frames past the 64 MiB parse cap before decoding, so a budget
-    // above it would admit a config whose honest child frames the host then
-    // silently discards.
+    // rejects raw frames past the 64 MiB parse cap (the run settles as a
+    // worker-exit), so a budget above it would admit a config whose honest
+    // child frames the host then rejects.
     const admissible = 64 * 1024 * 1024 - 64
     const ctx = new Context()
     await expect(ctx.plugin(PythonCodeRuntime, { maxLogBytes: admissible + 1 }))
@@ -2952,30 +2952,6 @@ describe('PythonCodeRuntime — budgets, termination, disposal', () => {
     expect(still).toBe(true)
   }, 20_000)
 
-  it('dispose resolves promptly when the kill empties the group and an orphan holds the pipes', async () => {
-    // The group-emptied arm of the reap poll: dispose() drives settle, kill()
-    // kills the still-running child, and a setsid orphan holds the pipes open
-    // so close never fires — the poll must run, see the group empty (the
-    // orphan escaped into its own session), cancel the pending grace SIGKILL,
-    // and finalize immediately. A prompt resolve proves the arm ran
-    // (fail-before: dropping clearTimeout/finalize from that arm leaves dispose
-    // waiting for the never-firing grace escalation and blows the bound).
-    const { runtime, fiber } = await setup({ maxWallMs: 60_000, graceMs: 60_000 })
-    const start = Date.now()
-    const runPromise = runtime.run({
-      program: [
-        'import subprocess, sys, time',
-        'subprocess.Popen([sys.executable, "-c", "import time; time.sleep(30)"],',
-        '                 start_new_session=True)',
-        'time.sleep(30)',
-      ].join('\n'),
-      bindings: [],
-    })
-    await fiber.dispose()
-    const result = await runPromise
-    expect(result.error?.kind).toBe('abort')
-    expect(Date.now() - start).toBeLessThan(5_000)
-  }, 20_000)
 
   it('dispose awaits reaping of a same-group survivor from a completed run', async () => {
     // The quiescence contract also holds for a run that ALREADY resolved: the run