refactor: rebrand decp.info to colibre #57

- Rename project from decp.info to colibre across all codebase
- Update domain from https://decp.info to https://colibre.fr
- Update GitHub repo references to ColinMaudry/colibre
- Rename deployment files: decpinfo-backup.* → colibre-backup.*
- Update project configuration and documentation
- Rename project assets: decp.info.png → colibre.png
- Update environment variables and constants (DOMAIN_NAME, TOKEN_PREFIX, GITHUB_REPO, etc.)
- Update URLs in all pages, tests, and configuration files
- Keep DECP acronym in text (unchanged per requirements)
- Add rebrand note to README.md

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

src/pages/recherche.py

@@ -12,7 +12,7 @@ NAME = "Recherche"
 register_page(
     __name__,
     path="/",
-    title="Recherche de marchés publics | decp.info",
+    title="Recherche de marchés publics | colibre",
     name=NAME,
     description="Explorez et analysez les données des marchés publics français avec cet outil libre et gratuit. Pour une commande publique accessible à toutes et tous.",
     image_url=META_CONTENT["image_url"],