fix(hooks): six defects in ModelRungGuard, VerificationGate, ISAFoldGate, EventLogger

[elhoim]

5 commits, one per fix, so each can be cherry-picked independently. Each was verified to apply cleanly onto 47df8ee by itself.

Commit	Fix
f06dec4	read only the transcript tail and skip sidechain rows
2f04673	let the verification gate split units on a newline between digits
aee48b3	decide hard-fail from is_error, not from words in the output
382ac46	stop ISAFoldGate reading a read-only command as a prod mutation
0a7551a	resolve the bun binary instead of spawning it bare

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Six defects under hooks/. These are guardrails, so each change is deliberately conservative: nothing previously blocked starts passing.

• ModelRungGuard.hook.ts:125 — liveModel() does not filter isSidechain, so a subagent's model reads as the main loop's. Dispatching to a lower rung injected a false "MODEL RUNG" warning and wrote a bogus off-pin telemetry row.
• ModelRungGuard.hook.ts:118 — read the entire transcript into memory before slicing TAIL_BYTES, contradicting the file's own "<20ms hot path" comment. Reads only the tail.
• VerificationGate.hook.ts:76 — the digit-lookaround split refuses to break on a newline between two digits, so unrelated lines merged into one "unit" that could satisfy both halves of a T5 block, defeating the gate.
• VerificationGate.hook.ts:222 — hard-fail was decided by a regex over resultText and never consulted is_error, so a successful rg -n "exit 1" tripped it via the new "command" event fallback.
• ISAFoldGate.hook.ts:48 — PROD_MUTATION_RES matched raw command text, so a read-only rg -n "Tools/Release.ts" counted as a production mutation and blocked Stop. The 120-char truncation separately cut real wrangler … INSERT commands past the match point.
• EventLogger.hook.ts:235 — spawned bare bun detached, the exact class hooks/lib/resolve-bin.ts was added this release to fix. ENOENT surfaced asynchronously past the sync try/catch, and the resulting missing state file made the self-heal fire on every tool call. Uses the helper.

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Testing. Commands and output are in the per-file notes above. I did not do a fresh-system install verification (contributing step 3) — these are targeted fixes verified per-file, not an install run.

[danielmiessler]

Thanks @elhoim — the six hook defects. Ported into the source tree (the public repo is generated from it, so I'm closing this here), credited by number at the fix site. Ships in the next release. I tightened the ISAFoldGate exemption a bit further on the way in — dropped less/bat and excluded rg --pre.