docs(process): stop overclaiming the pre-kill sample; drop a dead comment

Review round 5: one blocking, one major. Both documentation-only; the
runtime fixes from round 4 are unchanged.

**The pre-kill sample was overclaimed.** Acceptance 4 said the measured
group "describes the target that was attempted". It does not. `getpgid`
and `kill` remain separated by the same read-then-act window §1.5 is
built on, so the sample can be stale by the time the signal is
delivered. Moving it earlier removes a POST-HOC reading; it does not
make the reading contemporaneous. The criterion now says it records
pre-kill evidence about the attempted target, and adds an explicit
sentence forbidding any acceptance from claiming otherwise.

This is worth naming rather than quietly editing: the framing's whole
spine is that this telemetry establishes less than it appears to, and
round 4 fixed a real ordering defect and then inflated the fix's meaning
inside the document that governs it.

**`95897f7`'s commit message carries the same overclaim.** It is not
amended — force-pushing a branch under review to rewrite history would
hide the error rather than correct it. This message is the correction,
and the two read in sequence.

**A dead doc comment was documenting a constant.** The original
pre-Stage-B acceptance-1 block survived the rewrite and came to rest
above `const BASH`, so the file explained a string constant with the
sentence this entire lane exists to remove — "here they are asserted to
agree only because nothing has moved the terminal", describing a test
that no longer exists. Removed; only the BASH explanation remains.

Verified the overclaim is gone from the whole tree, not only the cited
line: no hits in `docs/` or `src/`.

Gates: 11 gates, 4,471 tests, zero failures.

docs/process-signal-diagnostic-completeness-framing.md

@@ -492,8 +492,15 @@ assertion (`:2517`) is one of the four sites acceptance 5 must update.
    field distinct from the assumed one, renderable as unobservable, with
    a test asserting a case where they **differ** (§3 Bet 4). **It is
    sampled before the `kill`**, not during report construction, so it
-   describes the target that was attempted rather than the state left
-   behind by the failure.
+   records pre-kill evidence about the target that was attempted rather
+   than state left behind by the failure.
+
+   **It does not describe the group at the moment the `kill` executed.**
+   `getpgid` and `kill` remain separated by the read-then-act window
+   §1.5 describes, so the sample can be stale by the time the signal is
+   delivered. Moving it earlier removes a *post-hoc* reading; it does
+   not make the reading contemporaneous, and no acceptance may claim it
+   does.
 5. All four exact-string sites — `:2408`, `:2435`, `:2485`, `:2517` —
    updated **individually**, each listed in the PR body with before and
    after. No blanket rewrite: that is how a format regression hides.

src/process.rs

@@ -2617,18 +2617,6 @@ mod tests {
         }
     }
 
-    /// Q#PD1 acceptance 1 — a group-directed failure names the target,
-    /// the branch that chose it, the expected group, the errno, and the
-    /// leader's own state, as five separate facts.
-    ///
-    /// Asserted as an exact message against the pid the kernel actually
-    /// assigned, so a hardcoded target could not satisfy it. The leader
-    /// field is the one that matters: for a PTY the signal goes to the
-    /// terminal's foreground group, a different entity from the spawned
-    /// child whenever job control has moved the terminal. Three rejected
-    /// designs for this code collapsed the two; the report keeps them
-    /// apart, and here they are asserted to agree only because nothing
-    /// has moved the terminal.
     /// The job-control shell the divergence fixture drives. Named once so
     /// the availability guard and the spawn cannot drift apart.
     const BASH: &str = "/bin/bash";