Fix lualatex stdin PDF gen + unit test for signed estimate PDF

GenerateEstimatePdf passed /dev/stdin as the input filename so lualatex
treats stdin as a regular input file instead of the terminal — without
it, lualatex emergency-stops after the first line of a multi-line
document (the real root cause of the production "Emergency stop", not
bera/luaotfload which were separate host-package gaps already fixed).

EstimatePdf endpoint calls GenerateEstimatePdf directly and streams the
returned FileInfo, guarding on fo.Exists. QueryAcceptanceRequest is
extracted into its own file under ViewModels/FrontOffice.

Add EstimatePdfGenerationTests: unit tests for SignatureToTikz (vector
draws of both signatures) and GenerateEstimatePdf on a devis signed by
both parties — asserts the PDF exists at the expected DestDir path, is
non-empty, and that only the PDF persists (aux/log cleaned). Skips
cleanly when lualatex is absent.

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

src/Yavsc.Api.Test/EstimatePdfGenerationTests.cs

@@ -0,0 +1,191 @@
+using System.Diagnostics;
+using System.Globalization;
+using System.IO;
+using System.Reflection;
+using Yavsc.Helpers;
+using Yavsc.Models.Billing;
+using Yavsc.ViewModels.Gen;
+
+namespace Yavsc.Api.Test;
+
+// Unit test of the estimate PDF generation pipeline (no HTTP fixture
+// needed): it exercises TeXHelpers.SignatureToTikz — the vector drawing
+// of the provider and client signatures — and TeXHelpers.GenerateEstimatePdf
+// — the lualatex stdin compile that writes <name>.pdf into DestDir. The
+// TeX source mirrors what the Estimate_tex template emits for a devis
+// signed by both parties: two side-by-side minipages, each with a
+// tikzpicture bounded by \useasboundingbox and the strokes drawn by
+// SignatureToTikz.
+//
+// The PDF test requires the system `lualatex` (and the TeX Live packages
+// listed in the README runtime-deps section) on the host running the
+// tests. On hosts without lualatex it skips cleanly rather than failing.
+public sealed class EstimatePdfGenerationTests
+{
+    // A provider signature: a downstroke, a cross, and a tap (dot).
+    // PostIt wire format — [k, x0,y0, x1,y1, …] per stroke, coords in
+    // [0, 10000], y-down.
+    private static readonly int[] ProStrokes =
+    {
+        4, 2000, 8000, 2000, 5000, 2000, 2000, 2100, 1900,
+        3, 2000, 5000, 3500, 4500, 3500, 5100,
+        1, 4000, 3000,
+    };
+
+    // A client signature: a wavy stroke and a shorter one.
+    private static readonly int[] CliStrokes =
+    {
+        5, 1000, 7000, 1500, 4000, 2200, 3000, 3000, 2500, 4000, 1500,
+        2, 3000, 6000, 4200, 5500,
+    };
+
+    [Fact]
+    public void SignatureToTikz_RendersBothSignaturesAsVectorDraws()
+    {
+        var pro = MakeSig(SignatureType.Pro, ProStrokes);
+        var cli = MakeSig(SignatureType.Client, CliStrokes);
+
+        var proTex = pro.SignatureToTikz(5, 2.5).ToString();
+        var cliTex = cli.SignatureToTikz(5, 2.5).ToString();
+
+        Assert.Contains("\\draw[line cap=round, line join=round, line width=1.5pt]", proTex);
+        Assert.Contains("\\fill", proTex);            // the single-point tap → dot
+        Assert.Contains("(1.000,0.500)", proTex);    // first point (2000,8000), y flipped
+        Assert.Contains("\\draw[line cap=round, line join=round, line width=1.5pt]", cliTex);
+        Assert.Contains("--", cliTex);
+    }
+
+    [Fact]
+    public void SignatureToTikz_EmptySignatureIsEmpty()
+    {
+        var empty = MakeSig(SignatureType.Pro, Array.Empty<int>());
+        Assert.Equal("", empty.SignatureToTikz(5, 2.5).ToString());
+    }
+
+    [Fact]
+    public void GenerateEstimatePdf_WithBothSignatures_ProducesPdfInDestDir()
+    {
+        if (!IsLualatexAvailable())
+            throw Xunit.Sdk.SkipException.ForSkip(
+                "lualatex is not installed on this host; skipping PDF generation test. " +
+                "Install the TeX Live runtime deps documented in the README.");
+
+        var destDir = Path.Combine(Path.GetTempPath(),
+            "yavsc-estimate-pdf-" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(destDir);
+
+        try
+        {
+            var pro = MakeSig(SignatureType.Pro, ProStrokes);
+            var cli = MakeSig(SignatureType.Client, CliStrokes);
+            var baseName = "estimate-test-both-signed";
+
+            var model = new PdfGenerationViewModel
+            {
+                TeXSource = BuildEstimateTeX(pro, cli),
+                BaseFileName = baseName,
+                DestDir = destDir,
+            };
+
+            var fo = model.GenerateEstimatePdf();
+
+            // The PDF must exist, at the expected path, and be non-empty.
+            var expectedPath = Path.Combine(destDir, baseName + ".pdf");
+            Assert.True(fo is not null && fo.Exists,
+                "GenerateEstimatePdf returned a non-existent file. Error: "
+                + model.GenerationErrorMessage?.Value);
+            Assert.Equal(expectedPath, fo.FullName);
+            Assert.True(fo.Length > 0, "generated PDF is empty");
+
+            // Only the PDF should persist in DestDir — aux/log artifacts
+            // are cleaned up by GenerateEstimatePdf on success.
+            var leftovers = Directory.GetFiles(destDir)
+                .Where(p => !Path.GetFileName(p).Equals(baseName + ".pdf", StringComparison.Ordinal))
+                .ToArray();
+            Assert.Empty(leftovers);
+        }
+        finally
+        {
+            if (Directory.Exists(destDir))
+                Directory.Delete(destDir, recursive: true);
+        }
+    }
+
+    private static Signature MakeSig(SignatureType type, int[] strokes)
+        => new()
+        {
+            Type = type,
+            CoordinateMax = 10_000,
+            Strokes = strokes,
+            CapturedAtUtc = new DateTime(2026, 9, 22, 0, 0, 0, DateTimeKind.Utc),
+        };
+
+    // Builds the LaTeX source the Estimate_tex template would emit for a
+    // devis signed by both parties: same preamble (incl. tikz + bera) and
+    // the two-minipage signature foot, with the strokes drawn by
+    // SignatureToTikz.
+    private static string BuildEstimateTeX(Signature pro, Signature cli)
+    {
+        var fr = CultureInfo.CreateSpecificCulture("fr-FR");
+        var date = new DateTime(2026, 9, 22).ToString("dddd dd MMMM yyyy", fr);
+        var proTikz = pro.SignatureToTikz(5, 2.5).ToString();
+        var cliTikz = cli.SignatureToTikz(5, 2.5).ToString();
+
+        return $@"\documentclass[french,11pt]{{article}}
+\usepackage{{eurosym}}
+\usepackage{{babel}}
+\usepackage[T1]{{fontenc}}
+\usepackage[utf8]{{inputenc}}
+\usepackage[a4paper]{{geometry}}
+\usepackage{{units}}
+\usepackage{{bera}}
+\usepackage{{graphicx}}
+\usepackage{{fancyhdr}}
+\usepackage{{fp}}
+\usepackage{{tikz}}
+\geometry{{verbose,tmargin=4em,bmargin=8em,lmargin=6em,rmargin=6em}}
+\setlength{{\parindent}}{{0pt}}
+\begin{{document}}
+Devis n°1 --- test signe par les deux parties
+
+\vspace{{2em}}
+\noindent
+\begin{{minipage}}[t]{{0.45\textwidth}}
+  \textbf{{Signature du fournisseur}}\\
+\small Valide le {date}\\
+\begin{{tikzpicture}}
+  \useasboundingbox (0,0) rectangle (5,2.5);
+  {proTikz}
+\end{{tikzpicture}}
+\end{{minipage}}\hfill
+\begin{{minipage}}[t]{{0.45\textwidth}}
+  \textbf{{Signature du client}}\\
+\small Valide le {date}\\
+\begin{{tikzpicture}}
+  \useasboundingbox (0,0) rectangle (5,2.5);
+  {cliTikz}
+\end{{tikzpicture}}
+\end{{minipage}}
+\end{{document}}
+";
+    }
+
+    private static bool IsLualatexAvailable()
+    {
+        try
+        {
+            using var p = Process.Start(new ProcessStartInfo("lualatex", "--version")
+            {
+                UseShellExecute = false,
+                RedirectStandardOutput = true,
+                RedirectStandardError = true,
+            });
+            if (p is null) return false;
+            return p.WaitForExit(5000) && p.ExitCode == 0;
+        }
+        catch
+        {
+            return false;
+        }
+    }
+}