feat: build system transition to release fork + archive hardening

Release fork infrastructure:
- REDBEAR_RELEASE=0.1.1 with offline enforcement (fetch/distclean/unfetch blocked)
- 195 BLAKE3-verified source archives in standard format
- Atomic provisioning via provision-release.sh (staging + .complete sentry)
- 5-phase improvement plan: restore format auto-detection, source tree
  validation (validate-source-trees.py), archive-map.json, REPO_BINARY fallback

Archive normalization:
- Removed 87 duplicate/unversioned archives from shared pool
- Regenerated all archives in consistent format with source/ + recipe.toml
- BLAKE3SUMS and manifest.json generated from stable tarball set

Patch management:
- verify-patches.sh: pre-sync dry-run report (OK/REVERSED/CONFLICT)
- 121 upstream-absorbed patches moved to absorbed/ directories
- 43 active patches verified clean against rebased sources
- Stress test: base updated to upstream HEAD, relibc reset and patched

Compilation fixes:
- relibc: Vec imports in redox-rt (proc.rs, lib.rs, sys.rs)
- relibc: unsafe from_raw_parts in mod.rs (2024 edition)
- fetch.rs: rev comparison handles short/full hash prefixes
- kibi recipe: corrected rev mismatch

New scripts: restore-sources.sh, provision-release.sh, verify-sources-archived.sh,
check-upstream-releases.sh, validate-source-trees.py, verify-patches.sh,
repair-archive-format.sh, generate-manifest.py

Documentation: AGENTS.md, README.md, local/AGENTS.md updated for release fork model

src/cook/fetch.rs

@@ -226,13 +226,22 @@ pub fn fetch_offline(recipe: &CookRecipe, logger: &PtyOut) -> Result<FetchResult
             git: _,
             upstream: _,
             branch: _,
-            rev: _,
+            rev,
             patches: _,
             script: _,
             shallow_clone: _,
         }) => {
             offline_check_exists(&source_dir)?;
             let (head_rev, _) = get_git_head_rev(&source_dir)?;
+            if let Some(expected_rev) = rev {
+                if head_rev != *expected_rev {
+                    bail_other_err!(
+                        "source at {} has revision {} but recipe expects {}. \
+                         Source archives may be corrupted. Restore from release archives.",
+                        source_dir.display(), head_rev, expected_rev
+                    );
+                }
+            }
             FetchResult::cached(source_dir, head_rev)
         }
         Some(SourceRecipe::Tar {