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

local/patches/kernel/P7-proc-setpriority.patch

@@ -11,7 +11,7 @@ diff --git a/src/scheme/proc.rs b/src/scheme/proc.rs
      Name,
  
      MmapMinAddr(Arc<AddrSpaceWrapper>),
-@@ -160,6 +161,17 @@ pub struct ProcScheme;
+@@ -160,7 +161,18 @@ pub struct ProcScheme;
  static NEXT_ID: AtomicUsize = AtomicUsize::new(1);
  static HANDLES: RwLock<L1, HashMap<usize, Handle>> =
      RwLock::new(HashMap::with_hasher(DefaultHashBuilder::new()));
@@ -38,7 +38,7 @@ diff --git a/src/scheme/proc.rs b/src/scheme/proc.rs
              "mmap-min-addr" => (
                  ContextHandle::MmapMinAddr(Arc::clone(
                      context
-@@ -1191,6 +1204,17 @@ impl ContextHandle {
+@@ -1191,6 +1204,18 @@ impl ContextHandle {
  
                  Ok(size_of_val(&mask))
              }