cmds.projects.lib.templates: Don't replace escaped markers

format_list_dict() substitutes {key} markers with str.replace(), which also
matches the marker inside ${key} and {{key}}, mangling text meant to
survive verbatim, e.g. the ${prefix} variable reference of a pkg-config
file. The built-in pkg-config template works around that with doubled
braces, which produces {/usr}-style output instead.

Replace the markers with a regular expression that skips markers preceded
by '$' or '{', and let the pkg-config template use the ${prefix} and
${exec_prefix} references pkg-config expects.

Extend the unit tests with marker escaping, value escaping, quoting,
indentation, and the rendering of the built-in templates.

Assisted-by: unsloth/Qwen3.8-27B-GGUF:Q4_K_M with pi.dev v0.84.2
Signed-off-by: Jan Lindemann <jan@janware.com>

src/python/jw/pkg/cmds/projects/lib/templates.py

@@ -1,3 +1,4 @@
+import re
 import textwrap
 
 from typing import Any, Iterable, TypeAlias, TypeGuard
@@ -95,12 +96,17 @@ def format_list_dict(
     parts = template.splitlines(keepends = True)
 
     for line in parts:
-        for key, value in fmt_dict.items():
-            marker = '{' + key + '}'
-            if marker in line:
-                indent = line[:line.index(marker)]
-                value = str(value).replace('\n', '\n' + indent)
-                line = line.replace(marker, value)
+        for key, val in fmt_dict.items():
+            # -- A marker preceded by '$' or '{' is literal text rather
+            # than a placeholder, so that e.g. ${prefix} survives as a
+            # pkg-config variable reference
+            rx = re.compile(r'(?<![${])\{' + re.escape(key) + r'\}')
+            m = rx.search(line)
+            if m is None:
+                continue
+            indent = line[:m.start()]
+            sub = str(val).replace('\n', '\n' + indent)
+            line = rx.sub(lambda _m: sub, line)
         ret.append(line)
 
     return ''.join(ret)
@@ -114,9 +120,9 @@ _templates = {
     'pkg-config':
     """\
         prefix = {prefix}
-        exec_prefix = {{prefix}}
-        includedir = {{prefix}}/include
-        libdir = {{exec_prefix}}/lib
+        exec_prefix = ${prefix}
+        includedir = ${prefix}/include
+        libdir = ${exec_prefix}/lib
 
         Name: {name}
         Description: {description}