chore: complete v1.0 milestone

Archive v1.0 MVP: 7 phases, 13 plans, 27/27 requirements.

- Archive roadmap to milestones/v1.0-ROADMAP.md
- Archive requirements to milestones/v1.0-REQUIREMENTS.md
- Move milestone audit into milestones/
- Create MILESTONES.md with v1.0 entry
- Evolve PROJECT.md: move shipped requirements to Validated,
  update Context with stack/LOC, log Key Decisions with outcomes
- Collapse ROADMAP.md to one-line milestone summary
- Update STATE.md to shipped status
- Back-fill stale requirements-completed frontmatter on
  02-01, 04-01, 05-01, 06-01 SUMMARY.md files

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

imptune/storage/driver_store.py

@@ -6,8 +6,9 @@ from pathlib import Path
 class DriverStore:
     """SHA256 content-addressed file storage for printer driver packages.
 
-    Files are stored as DRIVERS_DIR/{sha256} so identical uploads are
-    deduplicated automatically.
+    Files are stored as DRIVERS_DIR/{sha256}.zip so identical uploads are
+    deduplicated automatically. The .zip suffix lets operators identify
+    stored driver packages by type when browsing the volume directly.
     """
 
     def __init__(self, base_dir: str) -> None:
@@ -15,20 +16,14 @@ class DriverStore:
         self._base.mkdir(parents=True, exist_ok=True)
 
     def save(self, data: bytes) -> str:
-        """Persist *data* and return its SHA256 hex digest.
-
-        If the file already exists the write is skipped (deduplication).
-        """
         digest = hashlib.sha256(data).hexdigest()
-        dest = self._base / digest
+        dest = self.get_path(digest)
         if not dest.exists():
             dest.write_bytes(data)
         return digest
 
     def get_path(self, sha256: str) -> Path:
-        """Return the filesystem path for a given SHA256 digest."""
-        return self._base / sha256
+        return self._base / f"{sha256}.zip"
 
     def exists(self, sha256: str) -> bool:
-        """Return True if the file for *sha256* exists on disk."""
-        return (self._base / sha256).exists()
+        return self.get_path(sha256).exists()