feat(academic-periods): period selector, active period

API, holiday indicators; UI polish; bump version

Dashboard:

Add Syncfusion academic period dropdown next to group selector
Navigate scheduler to today's month/day within selected period year on change
Show adjacent holiday plan badge; keep "holidays in view" counter on the right
Compact dropdown widths for a tighter toolbar
Default blocking of scheduling on holidays; block entries styled like all-day; black text styling
API:

Add academic periods routes: list, get active, set active (POST), for_date
Register blueprint in wsgi
Holidays:

Support TXT/CSV upload; headerless TXT uses columns 2-4; region remains null
Docs:

Update shared Copilot instructions with academic periods endpoints and dashboard integration details

server/routes/holidays.py

@@ -24,9 +24,14 @@ def list_holidays():
 @holidays_bp.route("/upload", methods=["POST"])
 def upload_holidays():
     """
-    Accepts a CSV file upload (multipart/form-data) with columns like:
-    name,start_date,end_date,region
-    Dates can be in ISO (YYYY-MM-DD) or common European format (DD.MM.YYYY).
+    Accepts a CSV/TXT file upload (multipart/form-data).
+
+    Supported formats:
+    1) Headered CSV with columns (case-insensitive): name, start_date, end_date[, region]
+       - Dates: YYYY-MM-DD, DD.MM.YYYY, YYYY/MM/DD, or YYYYMMDD
+    2) Headerless CSV/TXT lines with columns:
+       [internal, name, start_yyyymmdd, end_yyyymmdd, optional_internal]
+       - Only columns 2-4 are used; 1 and 5 are ignored.
     """
     if "file" not in request.files:
         return jsonify({"error": "No file part"}), 400
@@ -35,26 +40,36 @@ def upload_holidays():
         return jsonify({"error": "No selected file"}), 400
 
     try:
-        content = file.read().decode("utf-8", errors="ignore")
-        # Try to auto-detect delimiter; default ','
+        raw = file.read()
+        # Try UTF-8 first (strict), then cp1252, then latin-1 as last resort
+        try:
+            content = raw.decode("utf-8")
+        except UnicodeDecodeError:
+            try:
+                content = raw.decode("cp1252")
+            except UnicodeDecodeError:
+                content = raw.decode("latin-1", errors="replace")
+
         sniffer = csv.Sniffer()
         dialect = None
         try:
-            dialect = sniffer.sniff(content[:1024])
+            sample = content[:2048]
+            # Some files may contain a lot of quotes; allow Sniffer to guess delimiter
+            dialect = sniffer.sniff(sample)
         except Exception:
             pass
-        reader = csv.DictReader(io.StringIO(
-            content), dialect=dialect) if dialect else csv.DictReader(io.StringIO(content))
-
-        required = {"name", "start_date", "end_date"}
-        if not required.issubset(set(h.lower() for h in reader.fieldnames or [])):
-            return jsonify({"error": "CSV must contain headers: name, start_date, end_date"}), 400
 
         def parse_date(s: str):
             s = (s or "").strip()
             if not s:
                 return None
-            # Try ISO first
+            # Numeric YYYYMMDD
+            if s.isdigit() and len(s) == 8:
+                try:
+                    return datetime.strptime(s, "%Y%m%d").date()
+                except ValueError:
+                    pass
+            # Common formats
             for fmt in ("%Y-%m-%d", "%d.%m.%Y", "%Y/%m/%d"):
                 try:
                     return datetime.strptime(s, fmt).date()
@@ -65,16 +80,18 @@ def upload_holidays():
         session = Session()
         inserted = 0
         updated = 0
-        for row in reader:
-            # Normalize headers to lower-case keys
-            norm = {k.lower(): (v or "").strip() for k, v in row.items()}
-            name = norm.get("name")
-            start_date = parse_date(norm.get("start_date"))
-            end_date = parse_date(norm.get("end_date"))
-            region = norm.get("region") or None
-            if not name or not start_date or not end_date:
-                continue
 
+        # First, try headered CSV via DictReader
+        dict_reader = csv.DictReader(io.StringIO(
+            content), dialect=dialect) if dialect else csv.DictReader(io.StringIO(content))
+        fieldnames_lower = [h.lower() for h in (dict_reader.fieldnames or [])]
+        has_required_headers = {"name", "start_date",
+                                "end_date"}.issubset(set(fieldnames_lower))
+
+        def upsert(name: str, start_date, end_date, region=None):
+            nonlocal inserted, updated
+            if not name or not start_date or not end_date:
+                return
             existing = (
                 session.query(SchoolHoliday)
                 .filter(
@@ -86,9 +103,7 @@ def upload_holidays():
                 )
                 .first()
             )
-
             if existing:
-                # Optionally update region or source_file_name
                 existing.region = region
                 existing.source_file_name = file.filename
                 updated += 1
@@ -102,6 +117,41 @@ def upload_holidays():
                 ))
                 inserted += 1
 
+        if has_required_headers:
+            for row in dict_reader:
+                norm = {k.lower(): (v or "").strip() for k, v in row.items()}
+                name = norm.get("name")
+                try:
+                    start_date = parse_date(norm.get("start_date"))
+                    end_date = parse_date(norm.get("end_date"))
+                except ValueError:
+                    # Skip rows with unparseable dates
+                    continue
+                region = (norm.get("region")
+                          or None) if "region" in norm else None
+                upsert(name, start_date, end_date, region)
+        else:
+            # Fallback: headerless rows -> use columns [1]=name, [2]=start, [3]=end
+            reader = csv.reader(io.StringIO(
+                content), dialect=dialect) if dialect else csv.reader(io.StringIO(content))
+            for row in reader:
+                if not row:
+                    continue
+                # tolerate varying column counts (4 or 5); ignore first and optional last
+                cols = [c.strip() for c in row]
+                if len(cols) < 4:
+                    # Not enough data
+                    continue
+                name = cols[1].strip().strip('"')
+                start_raw = cols[2]
+                end_raw = cols[3]
+                try:
+                    start_date = parse_date(start_raw)
+                    end_date = parse_date(end_raw)
+                except ValueError:
+                    continue
+                upsert(name, start_date, end_date, None)
+
         session.commit()
         session.close()
         return jsonify({"success": True, "inserted": inserted, "updated": updated})