refactor: parametrize pipeline cu --course flag + suport Vimeo/text

Un singur set de scripturi acum rulează pe orice curs configurat în
courses.py. Master rămâne la rădăcina repo (backward-compat M1-M6);
cursuri noi (ex. practitioner la shop.cursnlp.ro) primesc un root
dedicat (nlp-practitioner/) cu propriile artefacte.

- courses.py: config dict (master, practitioner) + course_paths() +
  validate_manifest_course() (manifest fără course_key = master).
- download.py: --course + --modules; trei tipuri de lecții (audio HTTP,
  Vimeo iframe via yt-dlp audio-only, text-only cu captură HTML);
  merge cu manifest existent în loc de replace; strip [Audio] pentru
  backward-compat paths.
- transcribe.py: --course + --modules; skip type==text; path-uri prin
  course_paths(); validare course_key.
- summarize.py: --course + --compile; template prompt folosește
  course['name']; scrie SUPORT_CURS.md cu LF explicit (WSL2 baseline).
- md_to_pdf.py: --course resolv-ă summaries_dir / pdf_dir per curs.
- run.bat: detectează master|practitioner ca primul argument,
  propagă --course la sub-scripturi; backward-compat run.bat [modules].
- requirements.txt: + yt-dlp.
- .gitignore: nlp-practitioner/audio/, audio_wav/, scratch_recon.py, tmp_recon/.
- tests/test_regression.sh: 5 gate-uri read-only (import, schema,
  disk-coherence, SUPORT_CURS byte-identic, cross-course isolation).

Regression curs master: PASS (manifest + SUPORT_CURS.md hash
identic cu baseline /tmp/suport_before.md).

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

courses.py

@@ -0,0 +1,80 @@
+"""
+Shared course configuration for the NLP Master pipeline.
+
+A single pipeline (download -> transcribe -> summarize -> pdf) runs on
+multiple courses by passing --course <key>. Scripts resolve all artifact
+paths against course["root"], so curs master remains in-place at repo root
+and subsequent courses land in their own subdirectory.
+"""
+from pathlib import Path
+
+COURSES = {
+    "master": {
+        "name": "NLP Master Practitioner Bucuresti 2025",
+        "base_url": "https://cursuri.aresens.ro",
+        "course_path": "/curs/26",
+        "login_path": "/login",
+        "env_user": "COURSE_USERNAME",
+        "env_pass": "COURSE_PASSWORD",
+        # Curs master stays at repo root for backward-compat with M1-M6 outputs.
+        "root": Path("."),
+    },
+    "practitioner": {
+        "name": "NLP Practitioner (cursnlp.ro)",
+        "base_url": "https://shop.cursnlp.ro",
+        "course_path": "/curs/50",
+        "login_path": "/login",
+        "env_user": "PRACTITIONER_USERNAME",
+        "env_pass": "PRACTITIONER_PASSWORD",
+        "root": Path("nlp-practitioner"),
+    },
+}
+
+
+def get_course(key: str) -> dict:
+    """Return course config by key; SystemExit on unknown key."""
+    if key not in COURSES:
+        raise SystemExit(
+            f"Unknown course '{key}'. Available: {sorted(COURSES)}"
+        )
+    c = dict(COURSES[key])
+    c["key"] = key
+    c["course_url"] = c["base_url"] + c["course_path"]
+    c["login_url"] = c["base_url"] + c["login_path"]
+    return c
+
+
+def course_paths(course: dict) -> dict:
+    """Resolve artifact paths under course['root']."""
+    root = course["root"]
+    return {
+        "root":            root,
+        "manifest":        root / "manifest.json",
+        "audio_dir":       root / "audio",
+        "wav_cache_dir":   root / "audio_wav",
+        "transcripts_dir": root / "transcripts",
+        "summaries_dir":   root / "summaries",
+        "pdf_dir":         root / "summaries" / "pdf",
+        "master_guide":    root / "SUPORT_CURS.md",
+    }
+
+
+def validate_manifest_course(manifest: dict, course_key: str) -> None:
+    """
+    Ensure a pre-existing manifest belongs to the course currently being run.
+
+    Legacy policy: a manifest without `course_key` (written before this refactor)
+    is treated as `master`. This keeps backward-compat with the existing
+    curs_26 manifest.json from M1-M6.
+    """
+    mck = manifest.get("course_key")
+    if mck is None:
+        effective = "master"
+    else:
+        effective = mck
+    if effective != course_key:
+        raise SystemExit(
+            f"Manifest belongs to course '{effective}' but --course='{course_key}'. "
+            f"Refusing to corrupt cross-course state. "
+            f"Delete {course_key}'s manifest to start fresh, or run with --course={effective}."
+        )