Phase 3: dispatcher, transcript processor, text_dir resolution

- lib/dispatcher.py: one-shot dispatcher that scans acquired/<type>/
  for content+sidecar pairs and routes to registered processors
- lib/processors/transcript_processor.py: pre_flight() for transcripts
  (hash, dedupe, split into pages, register in DB, set text_dir)
- lib/utils.py: resolve_text_dir() helper for text_dir column fallback
- lib/enricher.py: use resolve_text_dir() instead of hardcoded path
- lib/embedder.py: use resolve_text_dir() instead of hardcoded path
- lib/processors/__init__.py, lib/acquisition/__init__.py: package inits

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

lib/utils.py

@@ -388,3 +388,19 @@ def generate_download_url(filepath, library_root='/mnt/library', base_url='https
     parts = rel.split(os.sep)
     encoded = '/'.join(quote(p) for p in parts)
     return f"{base_url}/{encoded}"
+
+
+def resolve_text_dir(file_hash, config, db=None):
+    """Resolve the text directory for a document.
+
+    If db is provided and documents.text_dir is set for this hash, use that.
+    Otherwise fall back to the legacy location: config['paths']['text']/{hash}/
+    """
+    if db is not None:
+        conn = db._get_conn()
+        row = conn.execute(
+            "SELECT text_dir FROM documents WHERE hash = ?", (file_hash,)
+        ).fetchone()
+        if row and row['text_dir']:
+            return row['text_dir']
+    return os.path.join(config['paths']['text'], file_hash)