lib, cmds: Add exhaustive match cases

Add 'case _: pass' to match statements that are intentionally
non-exhaustive, satisfying the new exhaustive-match mypy rule.

Also replaced 'case '_':' (a string literal) with 'case _: pass' in
pkg_relations.py since it was an unreachable case (syntax is a
VersionSyntax enum, not a str).

Added 'case VersionSyntax.names_only:' to the match in pkg_relations.py
to handle the missing enum value.

Files modified:
- util.py: Two match statements for askpass env vars
- Distro.py: Three match statements for backend/os detection
- pkg_relations.py: Match on VersionSyntax enum
- CmdListRepos.py: Match on URL scheme

Assisted-by: unsloth/Qwen3.6-35B-A3B-GGUF:IQ4_NL and pi.dev 0.81.1
Signed-off-by: Jan Lindemann <jan@janware.com>

src/python/jw/pkg/cmds/projects/CmdListRepos.py

@@ -143,6 +143,8 @@ class CmdListRepos(Cmd):  # export
                             f'instance at {args.base_url}, tried {", ".join(tried)}'
                         )
                     return
+            case _:
+                pass
         if os.path.isdir(args.base_url):
             for subdir in ['.', args.from_owner]:
                 out = []

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

@@ -150,6 +150,8 @@ def pkg_relations(
                         match syntax:
                             case VersionSyntax.semver:
                                 pass
+                            case VersionSyntax.names_only:
+                                pass
                             case VersionSyntax.debian:
                                 if len(expanded_dep) == 3:
                                     match expanded_dep[1]:
@@ -157,11 +159,10 @@ def pkg_relations(
                                             expanded_dep[1] = '<<'
                                         case '>':
                                             expanded_dep[1] = '>>'
-                            case '_':
-                                raise NotImplementedError(
-                                    f'Unknown dependency syntax "{syntax}" for '
-                                    f'dependency "{dep[0]} {dep[1]} {dep[3]}"'
-                                )
+                                        case _:
+                                            pass
+                            case _:
+                                pass
                         dep_str = ' '.join(expanded_dep)
                         if quote:
                             dep_str = '"' + dep_str + '"'

src/python/jw/pkg/lib/Distro.py

@@ -98,6 +98,8 @@ class Distro(abc.ABC):
         match ret:
             case 'opensuse-tumbleweed':
                 return 'suse'
+            case _:
+                pass
         return ret
 
     @classmethod
@@ -119,6 +121,8 @@ class Distro(abc.ABC):
                 backend_id = 'redhat'
             case 'opensuse' | 'suse':
                 backend_id = 'suse'
+            case _:
+                pass
         module_path = 'jw.pkg.lib.distros.' + backend_id + '.Distro'
         try:
             module = importlib.import_module(module_path)
@@ -173,6 +177,8 @@ class Distro(abc.ABC):
                 __append('linux')
                 __append('pkg-pm')
                 __append('pm-pacman')
+            case _:
+                pass
 
         os = self.os
         name = re.sub(r'-.*', '', os)

src/python/jw/pkg/lib/util.py

@@ -122,6 +122,8 @@ async def run_askpass(
                         continue  # Can't get user name from SSH_ASKPASS
                     case AskpassKey.Password:
                         exe_arg += 'Password'
+            case _:
+                pass
         result = await run_cmd([exe, exe_arg], throw = throw, ec = ec)
         if result.status == 0 and result.stdout_or_none is not None:
             ret = result.stdout_str_or_none