Fix clippy warnings and add Gitea CI pipeline

Clippy fixes:
- clawhdf5-onion/reader.rs: introduce RawPage type alias to resolve
  type_complexity lint on revision_pages_raw return type
- clawsync-onion/iblt.rs: remove stray #[forbid(unsafe_code)] module
  attribute (crate-level forbid already in lib.rs; the module attr was
  useless and triggered the empty-line-after-attribute lint)
- clawsync-onion/differ.rs: replace ok_or_else(|| …) with ok_or(…)
  for non-lazily-constructed error values
- clawsync-cli/main.rs: accept &Path instead of &PathBuf in
  handle_hdf5_client to avoid unnecessary indirection

CI (.gitea/workflows/ci.yml):
- test job: cargo test --workspace (default + simd-cdc)
- lint job: cargo clippy -D warnings + cargo fmt --check
- msrv job: build + test on Rust 1.85 (workspace rust-version)
- publish-dry-run job: cargo publish --dry-run for clawsync-core

All 573 tests still passing after fixes.

Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

crates/clawsync-onion/src/differ.rs

@@ -96,7 +96,7 @@ pub fn packets_for_revisions(
         let summary = summaries
             .iter()
             .find(|s| s.revision == rev)
-            .ok_or_else(|| SyncOnionError::Onion(
+            .ok_or(SyncOnionError::Onion(
                 clawhdf5_onion::OnionError::RevisionNotFound(rev),
             ))?;
 
@@ -191,9 +191,9 @@ pub fn diff_revisions_merkle(
             .list_revisions()
             .into_iter()
             .find(|s| s.revision == rev)
-            .ok_or_else(|| {
-                SyncOnionError::Onion(clawhdf5_onion::OnionError::RevisionNotFound(rev))
-            })?;
+            .ok_or(SyncOnionError::Onion(
+                clawhdf5_onion::OnionError::RevisionNotFound(rev),
+            ))?;
 
         let raw_pages = local.revision_pages_raw(rev)?;
         let pages: Vec<OnionPage> = raw_pages

crates/clawsync-onion/src/iblt.rs

@@ -29,8 +29,6 @@
 //!
 //! arXiv 2402.02668, 2504.08314 — rateless IBLTs for set reconciliation.
 
-#[forbid(unsafe_code)]
-
 use xxhash_rust::xxh3::xxh3_64;
 
 // ─────────────────────────────────────────────────────────────────────────────