skip non-extractable subs (dvdsub/dvbsub/unknown), summarise ffmpeg errors

Abraham Lincoln crashed with exit 234 because the file had 14 dvd_subtitle
streams: our extraction dict only keyed on the long form (dvd_subtitle)
while jellyfin stores the short form (dvdsub), so the lookup fell back
to .srt, ffmpeg picked the srt muxer, and srt can't encode image-based
subs. textbook silent dict miss.

replaced the extension dict with an EXTRACTABLE map that pairs codec →
{ext, codecArg} and explicitly enumerates every codec we can route to a
single-file sidecar. everything else (dvd_subtitle/dvdsub, dvb_subtitle/
dvbsub, unknown codecs) is now skipped at command-build time. the plan
picks up a note like '14 subtitle(s) dropped: dvdsub (eng, est, ind,
kor, jpn, lav, lit, may, chi, chi, tha, vie, rus, ukr) — not extractable
to sidecar' so the user sees exactly what didn't make it.

also added extractErrorSummary in execute.ts: when a job errors, scan
the last 60 stderr lines for fatal keywords (Error:, Conversion failed!,
Unsupported, Invalid argument, Permission denied, No space left, …),
dedupe, prepend the summary to the job's stored output. the review_plan
notes get the same summary — surfaces the real cause next to the plan
instead of burying it under ffmpeg's 200-line banner.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

package.json

@@ -1,6 +1,6 @@
 {
 	"name": "netfelix-audio-fix",
-	"version": "2026.04.14.20",
+	"version": "2026.04.14.21",
 	"scripts": {
 		"dev:server": "NODE_ENV=development bun --hot server/index.tsx",
 		"dev:client": "vite",