feat(logs): per-job log-symlink jobs/<job_id>.log -> runs/<ts>.log (IDEA-063)

Run-logs in /var/log/agent/runs/ zijn timestamp-named, dus de output van
een specifieke job was alleen via grep te vinden. De map jobs/ bestond al
maar werd niet gevuld.

- run-agent.sh: geeft het run-log-pad door als RUN_LOG env-var aan
  run-one-job.ts.
- run-one-job.ts: legt direct na de claim een symlink
  jobs/<job_id>.log -> ../runs/<ts>.log. Relatief pad (overleeft de
  host bind-mount), best-effort (faalt de job nooit over een log-gemak).
- log-cleanup.sh: ruimt dangling per-job symlinks op met `find -xtype l`
  — nodig omdat rotate-logs.sh het doel na 24u gzipt (.log -> .log.gz)
  of na 30d verwijdert, en de bestaande `-type f` cleanup symlinks niet
  raakt.

Functioneel geverifieerd: symlink resolveert, dangling-prune werkt,
`-type f` negeert de symlink (geen voortijdige delete). run-one-job.ts
parseert schoon (node --check + type-strip).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

bin/run-one-job.ts

@@ -22,7 +22,8 @@
 //   3  = TOKEN_EXPIRED detected → run-agent.sh schrijft TOKEN_EXPIRED marker
 
 import { spawn, spawnSync } from 'node:child_process'
-import { mkdirSync, rmSync, writeFileSync } from 'node:fs'
+import { mkdirSync, rmSync, symlinkSync, writeFileSync } from 'node:fs'
+import { basename, join } from 'node:path'
 
 import { Client as PgClient } from 'pg'
 
@@ -196,6 +197,25 @@ async function main(): Promise<number> {
 
     log(`claimed job_id=${jobId}`)
 
+    // Per-job log: symlink jobs/<jobId>.log -> the runs/<timestamp>.log of
+    // this iteration. runs/ files are timestamp-named, so without this a job's
+    // output is only findable by grepping. run-agent.sh passes the run-log
+    // path via RUN_LOG. Relative target so it survives the host bind-mount.
+    // Best-effort — never fail the job over a log convenience. Dangling links
+    // (after the runs/ file is gzipped/deleted) are pruned by log-cleanup.sh.
+    const runLog = process.env.RUN_LOG
+    if (runLog) {
+      try {
+        const jobsDir = join(process.env.AGENT_LOG_DIR ?? '/var/log/agent', 'jobs')
+        mkdirSync(jobsDir, { recursive: true })
+        const linkPath = join(jobsDir, `${jobId}.log`)
+        rmSync(linkPath, { force: true })
+        symlinkSync(join('..', 'runs', basename(runLog)), linkPath)
+      } catch (err) {
+        log(`per-job log symlink skipped for ${jobId}: ${(err as Error).message}`)
+      }
+    }
+
     // 3. Resolve full context.
     let ctx: Awaited<ReturnType<typeof getFullJobContext>> = null
     try {