feat(v1.2.0): retry API, dernier commit, tri, coloration, export JSON

- client.py: _get_with_retry (max 2 retries, backoff lineaire), get_latest_commit
- collector.py: champ last_commit_date dans RepoData
- display.py: colonne "Dernier commit", _sort_repos (name/issues/release/activity),
  _colorize_milestone_due (rouge/jaune/vert selon echeance)
- cli.py: options --sort/-s et --format/-f (table/json)
- exporter.py: nouveau module, repos_to_dicts + export_json
- 88 tests (35 nouveaux), ruff clean

fixes #8, fixes #7, fixes #10, fixes #9, fixes #6

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/gitea_dashboard/cli.py

@@ -43,6 +43,21 @@ def parse_args(argv: list[str] | None = None) -> argparse.Namespace:
         default=None,
         help="Exclure les repos par nom (sous-chaine, insensible a la casse). Repeatable.",
     )
+    parser.add_argument(
+        "--sort",
+        "-s",
+        choices=["name", "issues", "release", "activity"],
+        default="name",
+        help="Critere de tri des repos (defaut: name).",
+    )
+    parser.add_argument(
+        "--format",
+        "-f",
+        choices=["table", "json"],
+        default="table",
+        dest="format",
+        help="Format de sortie (defaut: table).",
+    )
     return parser.parse_args(argv)
 
 
@@ -91,4 +106,9 @@ def main(argv: list[str] | None = None) -> None:
         console.print(f"[red]Erreur API : {msg}[/red]")
         sys.exit(1)
 
-    render_dashboard(repos)
+    if args.format == "json":
+        from gitea_dashboard.exporter import export_json
+
+        print(export_json(repos))  # noqa: T201
+    else:
+        render_dashboard(repos, sort_key=args.sort)