Windows uv venv local quarto install has problems with backslashes --- patch included!

Review share/filters/main.lua around compileTemplate, then reproduce the failure with a local uv venv on Windows and quarto-cli installed via uv pip. Confirm that a document compiles successfully and that the informative Lua error no longer occurs for paths containing .venv.

I have:

• searched the issue tracker for similar issues
• installed the latest version of Quarto CLI
• formatted my issue following the Bug Reports guide

Bug description

diff --git a/share/filters/main.lua b/share/filters/main.lua
--- a/share/filters/main.lua
+++ b/share/filters/main.lua
@@ -3040,7 +3040,11 @@ function isInlineEl(el)
 end
 
 function compileTemplate(template, meta)
-  local f = io.open(pandoc.utils.stringify(template), "r")
+  template = pandoc.utils.stringify(template)
+  -- Pandoc treats the separator before `.venv` as an escape while parsing
+  -- the title-block attribute on Windows. Restore the resulting missing one.
+  template = template:gsub("([^/\\])%.venv", "%1/.venv")
+  local f = io.open(template, "r")
   if f then
     local contents = f:read("*all")
     f:close()

Steps to reproduce

You create a local uv venv .venv, then install quarto-cli using uv pip install quarto-cli and it won't work unless you use that patch.

Actual behavior

complains about lua code. The error is not informative.

Expected behavior

actually compile a document

Your environment

• windows 10, powershell 7

Quarto check output

Quarto 1.9.38
[>] Checking environment information...
      Quarto cache location: C:\Users\reckoner\AppData\Local\quarto
[>] Checking versions of quarto binary dependencies...
      Pandoc version 3.8.3: OK
      Dart Sass version 1.87.0: OK
      Deno version 2.4.5: OK
      Typst version 0.14.2: OK
[>] Checking versions of quarto dependencies......OK
[>] Checking Quarto installation......OK
      Version: 1.9.38
      Path: D:\data_science\.venv\Lib\site-packages\quarto_cli\bin
      CodePage: 1252
[>] Checking tools....................OK
      TinyTeX: v2026.04
      Chromium: (not installed)
      Chrome Headless Shell: (not installed)
      VeraPDF: (not installed)
[>] Checking LaTeX....................OK
      Using: TinyTex
      Path: C:\Users\reckoner\AppData\Roaming\TinyTeX\bin\windows\
      Version: 2026
[>] Checking Chrome Headless....................OK
      Using: Chrome found on system
      Path: C:\Program Files (x86)\Microsoft\Edge\Application\msedge.exe
      Source: Windows Registry
[>] Checking basic markdown render....OK
[>] Checking R installation...........(None)
      Unable to locate an installed version of R.
      Install R from https://cloud.r-project.org/
[>] Checking Python 3 installation....(None)
      Unable to locate an installed version of Python 3.
      Install Python 3 from https://www.python.org/downloads/
[>] Checking Julia installation...