chore: version 2.0.0-alpha.4 + changelog + plan-4 completion doc

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

CHANGELOG.md

@@ -3,6 +3,40 @@
 All notable changes to Void 2.0 are documented here.
 Format: [Keep a Changelog](https://keepachangelog.com).
 
+## [2.0.0-alpha.4] — 2026-06-01
+
+### Added (Plan 4: Python void-workers)
+
+- **`void-workers.service`** — Python 3.13 service alongside `void-server`
+  on CT 311. psycopg-based pg-boss client matches Node's claim/finish
+  semantics via `SELECT ... FOR UPDATE SKIP LOCKED`. Forces
+  `client_encoding=UTF8` on every connection (void2-db cluster is
+  SQL_ASCII).
+- **`extract.pdf`** — `pdftotext -layout` first; per-page `pdftoppm`
+  rasterization + Tesseract OCR fallback when extraction yields
+  < 200 chars.
+- **`extract.image`** — Tesseract OCR (English) for images stored in
+  the blob store.
+- **`ingest.video`** — `yt-dlp` metadata + audio extract + faster-whisper
+  (`small.en` default). CUDA at startup; CPU fallback when HA failover
+  to Z3 (no GPU) happens. URLs validated as http(s) and `--` separator
+  passed to yt-dlp to defeat argv smuggling.
+- **`sync.source_doc`** — fetches `upstream_url` via Python `safe_fetch`
+  (port of the Node helper) + sha256-diffs against the prior body_sha
+  in metadata; updates body_text only when content changed.
+- **Node `blob.js`** fans out to `extract.pdf` / `extract.image` after
+  creating PDF / image refs.
+- **Node `capture.js`** routes `youtube.com` / `youtu.be` / `vimeo.com`
+  URLs to `ingest.video` instead of `ingest.url`.
+- **Daily cron** (`lib/cron/sync_source_docs.js`) enqueues
+  `sync.source_doc` jobs at 03:00 local for every `source_docs` row
+  with `sync_source='url'`.
+- **CT 311 infrastructure**: resized to 6 cores / 8 GB RAM, NVIDIA
+  RTX A2000 device-nodes passed through (shared with CT 102's Ollama).
+- **`deploy/push-workers.sh`** + `deploy/void-workers.service` — push
+  the workers package, chown to `voidworkers`, recreate the venv, install
+  deps under `su voidworkers -c`, restart the unit.
+
 ## [2.0.0-alpha.3] — 2026-06-01
 
 ### Added (Plan 3: Capture pipeline + hybrid search)