fix: sub-agent hang/crash stranding runs mid-phase with no save

A stalled sub-agent (provider stream never settling after the final tool
call, or a throwing session-event listener recursing through the SDK's
run-failure path to stack overflow) left the phase stuck in_progress with
no state save, no error, and no completion message — observed twice in
freno-dev, both times after comments wrote findings.md.

- agent-runner: 60-min settle watchdog on every agent phase
  (PYGIENIUM_AGENT_TIMEOUT_MS, env-tunable); timeout disposes the session
  and fails the phase loudly with a /pygienium-resume hint instead of
  hanging the check-runner's await forever.
- agent-runner: applySessionEvent — the session.subscribe listener can no
  longer throw into the SDK event pipeline (guards for partial/malformed
  events, optional-chained message_update, throwing chat forwarder).
- comments: scan no longer regenerates the full report as its final
  message (findings.md is the source of truth); fix phase reads
  findings.md with embedded fallback.
- check-runner: failing state-save inside the catch path can't double-
  fault or escape as an unhandled rejection; completion posting is
  best-effort.
- tests: watchdog timeout test, comments task-text regression tests,
  applySessionEvent malformed-shape unit tests. 146 pass, tsc clean.
- README: document PYGIENIUM_AGENT_TIMEOUT_MS.

src/checks/comments.ts

@@ -92,8 +92,11 @@ ${scopeRulesMarkdown()}
 3. Apply the rubric below to each comment and classify it: RESTATE, VERBOSE,
    WHY, or OK.
 4. Write a findings report to \`${findingsFile}\` with per-file line refs.
-5. Return the findings report text as your final message (same content as the
-   file). The host captures it as the analysis-phase findings.
+5. Return a ONE-LINE summary as your final message, e.g.
+   \`<count> comment smell(s) across <files> file(s).\` The full report lives
+   in findings.md — do NOT regenerate the report text in your final message
+   (regenerating a large report doubles the fragile output right after the
+   file write and can stall the run).
 
 ${RUBRIC}
 
@@ -110,7 +113,8 @@ ${RUBRIC}
 \`\`\`
 
 If no smells are found, write \`# comments — findings\n\n0 comment smell(s).\`
-and return that text. Always create findings.md so the run has an artifact.
+and return \`0 comment smell(s).\` as your final message. Always create
+findings.md so the run has an artifact.
 
 Write the report under \`${outDir}\` (create directories as needed).
 `;
@@ -128,6 +132,7 @@ export function buildCommentsFixTask(
 ): string {
 	const outDir = commentsArtifactDir(scope);
 	const changesFile = changesPath(scope);
+	const findingsFile = findingsPath(scope);
 	return `# Task: comments hygiene fix
 
 You are running the **comments** hygiene fix phase.
@@ -136,6 +141,9 @@ You are running the **comments** hygiene fix phase.
 - Fix target: \`${scope.target}\`
 
 ## Input: scan findings
+Read the detailed per-file findings from \`${findingsFile}\` (created by the
+scan phase). If that file is missing or unreadable, fall back to the findings
+text below:
 ${findings.trim().length > 0 ? findings : "(no findings text provided)"}
 
 ## What to do