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>

test/unit/python/jw/pkg/cmds/projects/lib/templates/test.py

@@ -1,9 +1,14 @@
+import os
+import tempfile
+
 from jw.pkg.cmds.projects.lib.templates import (
+    format_list_dict,
     is_list_dict,
     is_str_dict,
     is_tuple_list,
     merge_values,
     render_values_to_list_dict,
+    tmpl_render,
 )
 
 # -- Type guards --
@@ -47,6 +52,85 @@ try:
 except Exception:
     pass
 
+# -- format_list_dict --
+
+# A plain {key} marker is substituted
+assert format_list_dict('a {key} b', {'key': ['x', 'y']}, False, ', ') == \
+    'a x, y b'
+
+# ${key} is a literal, e.g. a pkg-config variable reference
+assert format_list_dict(
+    'exec_prefix = ${prefix}', {'prefix': ['/usr']}, False, '\n'
+) == 'exec_prefix = ${prefix}'
+
+# {{key}} is a literal, too
+assert format_list_dict('{{prefix}}', {'prefix': ['/usr']}, False, '\n') == \
+    '{{prefix}}'
+
+# A ${key} next to a real marker: only the marker is substituted
+assert format_list_dict('x = {p} ${p}', {'p': ['v']}, False, '\n') == \
+    'x = v ${p}'
+
+# Backslashes in the value are not treated as regex replacements
+assert format_list_dict('{p}', {'p': ['a\\b', 'c$1']}, False, '\n') == \
+    'a\\b\nc$1'
+
+# li_quote wraps each list element in double quotes
+assert format_list_dict('{p}', {'p': ['a', 'b']}, True, ',\n') == \
+    '"a",\n"b"'
+
+# Multi-line values are re-indented to the marker position
+assert format_list_dict('  {p}', {'p': ['x\ny']}, False, '\n') == '  x\n  y'
+
+# String values pass through unsplit
+assert format_list_dict('{p}', {'p': 'xyz'}, False, '\n') == 'xyz'
+
+# -- tmpl_render --
+
+# The built-in pkg-config template renders a valid .pc file
+expected_pc = (
+    'prefix = /usr\n'
+    'exec_prefix = ${prefix}\n'
+    'includedir = ${prefix}/include\n'
+    'libdir = ${exec_prefix}/lib\n'
+    '\n'
+    'Name: jw-pkg\n'
+    'Description: desc\n'
+    'Version: 1.0\n'
+)
+assert tmpl_render(
+    'pkg-config',
+    [{
+        'prefix': '/usr', 'name': 'jw-pkg', 'description': 'desc', 'version': '1.0'
+    }]
+) == expected_pc
+
+# A template file from the search path wins over the built-ins
+with tempfile.TemporaryDirectory() as tmp:
+    path = os.path.join(tmp, 'my-tmpl')
+    with open(path, 'w') as f:
+        f.write('hello {who}\n')
+    assert tmpl_render(
+        'my-tmpl', [{
+            'who': 'world'
+        }], search_path = [tmp]
+    ) == 'hello world\n'
+
+# A missing template falls back to the built-ins
+with tempfile.TemporaryDirectory() as tmp:
+    assert tmpl_render(
+        'pkg-config', [{
+            'prefix': '/usr'
+        }], search_path = [tmp]
+    ).startswith('prefix = /usr\n')
+
+# An unknown template without search path raises
+try:
+    tmpl_render('no-such-template', [])
+    assert False, 'Should have raised'
+except Exception:
+    pass
+
 # -- merge_values --
 
 # String values are merged as whole strings, not character by character
@@ -70,4 +154,4 @@ assert merge_values(
     'a': ['x', 'y', 'z'], 'b': ['w']
 }
 
-print('All templates merge tests passed')
+print('All templates tests passed')