Make cache robust to removed archives (#6284)

## Summary

Closes https://github.com/astral-sh/uv/issues/6147.

## Test Plan

- `cargo run pip install flask --no-binary flask --cache-dir foo
--reinstall`
- `rm -rf foo/archive-v0`
- `cargo run pip install flask --no-binary flask --cache-dir foo
--reinstall`

crates/uv-distribution/src/archive.rs

@@ -1,6 +1,6 @@
 use distribution_types::Hashed;
 use pypi_types::HashDigest;
-use uv_cache::ArchiveId;
+use uv_cache::{ArchiveId, Cache};
 
 /// An archive (unzipped wheel) that exists in the local cache.
 #[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
@@ -16,6 +16,11 @@ impl Archive {
     pub(crate) fn new(id: ArchiveId, hashes: Vec<HashDigest>) -> Self {
         Self { id, hashes }
     }
+
+    /// Returns `true` if the archive exists in the cache.
+    pub(crate) fn exists(&self, cache: &Cache) -> bool {
+        cache.archive(&self.id).exists()
+    }
 }
 
 impl Hashed for Archive {

crates/uv-distribution/src/distribution_database.rs

@@ -596,8 +596,12 @@ impl<'a, Context: BuildContext> DistributionDatabase<'a, Context> {
                 CachedClientError::Client(err) => Error::Client(err),
             })?;
 
-        // If the archive is missing the required hashes, force a refresh.
-        let archive = if archive.has_digests(hashes) {
+        // If the archive is missing the required hashes, or has since been removed, force a refresh.
+        let archive = Some(archive)
+            .filter(|archive| archive.has_digests(hashes))
+            .filter(|archive| archive.exists(self.build_context.cache()));
+
+        let archive = if let Some(archive) = archive {
             archive
         } else {
             self.client
@@ -746,12 +750,16 @@ impl<'a, Context: BuildContext> DistributionDatabase<'a, Context> {
                 CachedClientError::Client(err) => Error::Client(err),
             })?;
 
-        // If the archive is missing the required hashes, force a refresh.
-        let archive = if archive.has_digests(hashes) {
+        // If the archive is missing the required hashes, or has since been removed, force a refresh.
+        let archive = Some(archive)
+            .filter(|archive| archive.has_digests(hashes))
+            .filter(|archive| archive.exists(self.build_context.cache()));
+
+        let archive = if let Some(archive) = archive {
             archive
         } else {
             self.client
-                .managed(|client| async move {
+                .managed(|client| async {
                     client
                         .cached_client()
                         .skip_cache(self.request(url)?, &http_entry, download)