feat: v3.0 - canvas editor, JSON-only, no Excel, new UI

- Remove all Excel code (import, export, template, pandas, openpyxl)
- New canvas-based schedule editor with drag & drop (interact.js)
- Modern 3-panel UI: sidebar, canvas, documentation tab
- New data model: Block with id/date/start/end, ProgramType with id/name/color
- Clean API: GET /api/health, POST /api/validate, GET /api/sample, POST /api/generate-pdf
- Rewritten PDF generator using ScenarioDocument directly (no DataFrame)
- Professional PDF output: dark header, colored blocks, merged cells, legend, footer
- Sample JSON: "Zimní výjezd oddílu" with 11 blocks, 3 program types
- 30 tests passing (API, core models, PDF generation)

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

app/api/pdf.py

@@ -2,12 +2,11 @@
 
 from io import BytesIO
 
-import pandas as pd
 from fastapi import APIRouter, HTTPException
 from fastapi.responses import StreamingResponse
 
 from app.models.event import ScenarioDocument
-from app.core.validator import validate_inputs, ValidationError, ScenarsError
+from app.core.validator import ScenarsError
 from app.core.pdf_generator import generate_pdf
 
 router = APIRouter()
@@ -17,35 +16,7 @@ router = APIRouter()
 async def generate_pdf_endpoint(doc: ScenarioDocument):
     """Generate PDF timetable from ScenarioDocument."""
     try:
-        validate_inputs(doc.event.title, doc.event.detail, 0)
-    except ValidationError as e:
-        raise HTTPException(status_code=422, detail=str(e))
-
-    # Convert to DataFrame
-    rows = []
-    for block in doc.blocks:
-        rows.append({
-            'Datum': block.datum,
-            'Zacatek': block.zacatek,
-            'Konec': block.konec,
-            'Program': block.program,
-            'Typ': block.typ,
-            'Garant': block.garant,
-            'Poznamka': block.poznamka,
-        })
-
-    df = pd.DataFrame(rows)
-
-    if df.empty:
-        raise HTTPException(status_code=422, detail="No blocks provided")
-
-    # Build program descriptions and colors
-    program_descriptions = {pt.code: pt.description for pt in doc.program_types}
-    program_colors = {pt.code: 'FF' + pt.color.lstrip('#') for pt in doc.program_types}
-
-    try:
-        pdf_bytes = generate_pdf(df, doc.event.title, doc.event.detail,
-                                 program_descriptions, program_colors)
+        pdf_bytes = generate_pdf(doc)
     except ScenarsError as e:
         raise HTTPException(status_code=422, detail=str(e))