Add cost/time estimate card to job detail page

app/estimation.py:
  - 20% infill → material volume → weight (density per material)
  - print time at 20 g/h (conservative FDM average)
  - filament cost at FILAMENT_PRICE_PER_KG EUR/kg (env, default 15)
  - +20% misprint buffer, +30% gross profit margin
  - net price (ex. VAT) and gross price (VAT_RATE %, env, default 19)

Card shows three columns: Material & Time / Production cost / Suggested price.
Only rendered when STL volume is available. Assumptions shown in card header.

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

.env.install

@@ -6,3 +6,5 @@ MYSQL_PASSWORD=
 STL_UPLOAD_DIR=/data/stl
 TZ=Europe/Berlin
 FILAMENTDB_URL=https://web.filamentdb.orb.local
+VAT_RATE=19
+FILAMENT_PRICE_PER_KG=15

app/estimation.py

@@ -0,0 +1,55 @@
+"""Job cost and time estimation from STL geometry."""
+import os
+
+# g/cm³ per material — used to convert volume → weight
+_DENSITY: dict[str, float] = {
+    "PLA":   1.24,
+    "PETG":  1.27,
+    "ABS":   1.04,
+    "ASA":   1.07,
+    "TPU":   1.20,
+    "Nylon": 1.14,
+    "PC":    1.20,
+}
+_DEFAULT_DENSITY = 1.24
+
+# Conservative average FDM print speed for weight-based time estimate
+_PRINT_SPEED_G_PER_HOUR = 20.0
+
+
+def estimate(volume_ccm: float, material: str | None) -> dict:
+    """
+    Returns a cost/time estimate dict for one job.
+
+    Assumptions:
+      - 20 % infill  →  material used = volume * 0.20
+      - filament density from _DENSITY (default 1.24 g/cm³)
+      - print speed: 20 g/h (conservative FDM average)
+      - filament cost: FILAMENT_PRICE_PER_KG EUR / kg  (env, default 15)
+      - misprint buffer: +20 %
+      - gross profit margin: +30 %
+      - VAT: VAT_RATE %  (env, default 19)
+    """
+    vat_rate      = float(os.environ.get("VAT_RATE", 19))
+    price_per_kg  = float(os.environ.get("FILAMENT_PRICE_PER_KG", 15))
+    density       = _DENSITY.get(material or "", _DEFAULT_DENSITY)
+
+    material_ccm  = volume_ccm * 0.20
+    weight_g      = material_ccm * density
+    print_minutes = round((weight_g / _PRINT_SPEED_G_PER_HOUR) * 60)
+
+    filament_cost = weight_g / 1000 * price_per_kg
+    after_misprint = filament_cost * 1.20
+    net_price     = after_misprint * 1.30
+    gross_price   = net_price * (1 + vat_rate / 100)
+
+    return {
+        "material_ccm":    round(material_ccm, 2),
+        "weight_g":        round(weight_g, 1),
+        "print_minutes":   print_minutes,
+        "filament_cost":   round(filament_cost, 2),
+        "net_price":       round(net_price, 2),
+        "gross_price":     round(gross_price, 2),
+        "vat_rate":        vat_rate,
+        "price_per_kg":    price_per_kg,
+    }

app/routers/ui.py

@@ -21,6 +21,7 @@ from app.models.printer_type import PrinterType
 from app.models.pricing import PricingConfig
 from app.models.todo import Todo
 from app.constants import COLORS, MATERIALS
+from app.estimation import estimate
 from app.filamentdb import available_colors, available_materials, get_stock, spool_counts
 from app.stl import get_stl_dir, list_stl_files
 from app.stl_analysis import analyse, get_cache_map  # noqa: F401 used in job_detail route
@@ -247,11 +248,13 @@ def job_detail(job_id: int, request: Request, db: Session = Depends(get_db)):
     if not job:
         raise HTTPException(status_code=404, detail="Job not found")
     stl = db.query(StlCache).filter_by(filename=job.file_name).first() if job.file_name else None
+    estimation = estimate(stl.volume_ccm, job.job_material) if stl and stl.volume_ccm else None
     return templates.TemplateResponse("job_detail.html", {
         "request": request,
         "active": "jobs",
         "job": job,
         "stl": stl,
+        "estimation": estimation,
         "printers": db.query(Printer).order_by(Printer.name).all(),
         "brackets": db.query(JobBracket).order_by(JobBracket.name).all(),
         "materials": available_materials() or MATERIALS,

app/templates/job_detail.html

@@ -111,6 +111,66 @@
 
 </div>
 
+{# ── Estimate ── #}
+{% if estimation %}
+<div class="card mb-4">
+  <div class="card-header text-secondary small text-uppercase fw-normal" style="border-color:#21262d">
+    Estimate
+    <span class="text-secondary fw-normal ms-2" style="font-size:.7rem">
+      20 % infill · {{ estimation.price_per_kg }} €/kg · {{ estimation.vat_rate }}% VAT
+    </span>
+  </div>
+  <div class="card-body">
+    <div class="row g-3">
+
+      <div class="col-md-4">
+        <div class="text-secondary small mb-2">Material &amp; Time</div>
+        <table class="table table-dark table-sm mb-0" style="font-size:.875rem">
+          <tbody>
+            <tr><td class="text-secondary border-0">Volume used</td>
+                <td class="border-0">{{ estimation.material_ccm }} cm³</td></tr>
+            <tr><td class="text-secondary">Weight</td>
+                <td>{{ estimation.weight_g }} g</td></tr>
+            <tr><td class="text-secondary">Print time</td>
+                <td>
+                  {% set h = (estimation.print_minutes // 60) %}
+                  {% set m = (estimation.print_minutes % 60) %}
+                  {% if h %}{{ h }}h {% endif %}{{ m }}min
+                  <span class="text-secondary" style="font-size:.75rem">(est.)</span>
+                </td></tr>
+          </tbody>
+        </table>
+      </div>
+
+      <div class="col-md-4">
+        <div class="text-secondary small mb-2">Production cost</div>
+        <table class="table table-dark table-sm mb-0" style="font-size:.875rem">
+          <tbody>
+            <tr><td class="text-secondary border-0">Filament</td>
+                <td class="border-0">{{ "%.2f"|format(estimation.filament_cost) }} €</td></tr>
+            <tr><td class="text-secondary">+ 20 % misprint</td>
+                <td>{{ "%.2f"|format(estimation.filament_cost * 1.2) }} €</td></tr>
+          </tbody>
+        </table>
+      </div>
+
+      <div class="col-md-4">
+        <div class="text-secondary small mb-2">Suggested price</div>
+        <table class="table table-dark table-sm mb-0" style="font-size:.875rem">
+          <tbody>
+            <tr><td class="text-secondary border-0">Net (ex. VAT)</td>
+                <td class="border-0 fw-medium text-white">{{ "%.2f"|format(estimation.net_price) }} €</td></tr>
+            <tr><td class="text-secondary">Gross ({{ estimation.vat_rate }}% VAT)</td>
+                <td class="fw-medium text-white">{{ "%.2f"|format(estimation.gross_price) }} €</td></tr>
+          </tbody>
+        </table>
+      </div>
+
+    </div>
+  </div>
+</div>
+{% endif %}
+
 {# ── Log ── #}
 <div class="d-flex align-items-center justify-content-between mb-3">
   <h6 class="text-white mb-0">Log</h6>