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/docs/XHCID-DEVICE-IMPROVEMENT-PLAN.md

@@ -303,7 +303,7 @@ Close the loop with evidence, canonical docs, and durable patch carriers.
 - update canonical docs:
   - `local/docs/USB-IMPLEMENTATION-PLAN.md`
   - `local/docs/USB-VALIDATION-RUNBOOK.md`
-- refresh durable patch carriers under `local/patches/base/`
+- immutable archived durable patch carriers under `local/patches/base/`
 - delete only clearly stale, superseded docs after link sweep
 
 ### Exit Criteria
@@ -311,7 +311,7 @@ Close the loop with evidence, canonical docs, and durable patch carriers.
 - all bounded USB/xHCI proofs pass on a fresh image
 - changed files are diagnostics-clean
 - canonical docs match actual proof scope
-- patch carrier is refreshed and reapplicable
+- patch carrier is immutable archived and reapplicable
 
 ## Validation Matrix
 
@@ -356,5 +356,5 @@ This work is complete only when:
 - `xhcid` builds/tests cleanly
 - bounded QEMU proof matrix passes on a rebuilt image
 - canonical docs are synchronized
-- durable patch carrier is refreshed
+- durable patch carrier is immutable archived
 - remaining gaps, if any, are explicitly documented as future or hardware-only work