refactor(structure): promote app to repo root + remove redundant workspace cruft

Standard production layout: the OKR app (was nested under AINative_OKR_CASAN5/) is now
the repository root. No more wrapper directory.

- Promote AINative_OKR_CASAN5/* -> repo root (backend/ frontend/ packages/ apps/
  .specify/ docs/ infra/ nginx/ scripts/ + configs). Merge tool dirs: .gitea (kept the
  active deploy ci.yml, added harness-ci.yml + runbooks), .claude (agents/commands +
  launch.json), .github moved up.
- Remove redundant: 00_SUBMISSION_PACKAGE, scattered root notes (FPT_CASAN_Full.md,
  tu-tuong-casan.md, casan-tu-sinh..., casan_harness_assessment.md, source-review...,
  README_CASAN5_REFINED.md), casan-next-plans/ and optimize-docs/ (competition/planning
  artifacts — roadmap + design history preserved in git log / commit messages).
- Update all references to the old layout:
  - .gitea/workflows/{ci,harness-ci}.yml, .github/workflows/{ci,deploy}.yml:
    working-directory .; drop AINative_OKR_CASAN5/ prefix; .specify/{tests,scripts}
    -> packages/casan-harness/... (.specify/logs state kept)
  - .claude/launch.json, .gitea/*-runbook.md: path prefixes
  - CLAUDE.md, README.md: docs/input -> apps/okr/domain/input
  - policy-bundle.yaml: 8 policy paths -> packages/casan-harness/...; manifest re-signed
- secrets-scan.sh: fixture excludes -> new package/domain paths.

Full gate from the new root: PASS=64 FAIL=0 SKIP=3.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/casan-harness/scripts/bash/verify-tool-audit.sh

@@ -0,0 +1,72 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Verify the tamper-evident central tool-call audit log:
+#   1. recompute the SHA-256 hash chain
+#   2. confirm the stored head equals the computed head
+#   3. verify the head's RSA signature
+# Usage: verify-tool-audit.sh [tool-calls.jsonl]
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+source "$SCRIPT_DIR/casan-paths.sh"
+PROJECT_ROOT="$CASAN_APP_ROOT"
+LOG="${1:-$CASAN_STATE_ROOT/logs/audit/tool-calls.jsonl}"
+
+if [[ ! -f "$LOG" ]]; then
+  echo "TOOL_AUDIT_MISSING file=$LOG" >&2
+  exit 1
+fi
+
+COMPUTED_HEAD="$(python - "$LOG" <<'PY'
+import hashlib, json, sys
+path = sys.argv[1]
+prev = ""
+count = 0
+with open(path, encoding="utf-8") as f:
+    for line_no, line in enumerate(f, 1):
+        if not line.strip():
+            continue
+        rec = json.loads(line)
+        if rec.get("previous_record_hash", "") != prev:
+            raise SystemExit(f"TOOL_AUDIT_CHAIN_BROKEN line={line_no}")
+        stored = rec.pop("record_hash", "")
+        core = json.dumps(rec, sort_keys=True, separators=(",", ":"))
+        expected = hashlib.sha256((prev + "|" + core).encode()).hexdigest()
+        if expected != stored:
+            raise SystemExit(f"TOOL_AUDIT_HASH_MISMATCH line={line_no}")
+        prev = stored
+        count += 1
+sys.stderr.write(f"TOOL_AUDIT_INTEGRITY_OK records={count}\n")
+sys.stdout.write(prev)
+PY
+)"
+
+AUDIT_DIR="$(dirname "$LOG")"
+HEAD_FILE="$AUDIT_DIR/tool-calls-head.txt"
+HEAD_SIG="$AUDIT_DIR/tool-calls-head.sig"
+AUDIT_PUB="$CASAN_GOVERNANCE_ROOT/audit-public.pem"
+
+if [[ -f "$HEAD_FILE" && -f "$HEAD_SIG" && -f "$AUDIT_PUB" ]] && command -v openssl >/dev/null 2>&1; then
+  if [[ "$(cat "$HEAD_FILE")" != "$COMPUTED_HEAD" ]]; then
+    echo "TOOL_AUDIT_HEAD_MISMATCH computed=$COMPUTED_HEAD" >&2
+    exit 1
+  fi
+  if ! openssl dgst -sha256 -verify "$AUDIT_PUB" -signature "$HEAD_SIG" "$HEAD_FILE" >/dev/null 2>&1; then
+    echo "TOOL_AUDIT_HEAD_SIGNATURE_INVALID head=$COMPUTED_HEAD" >&2
+    exit 1
+  fi
+  echo "TOOL_AUDIT_VALID anchor=signed last_hash=$COMPUTED_HEAD"
+else
+  # SEC-01 (H-01): enforced mode treats a missing/unverifiable signature as FAIL.
+  # Self-contained (this script is copied into sandboxes by tests — no common.sh).
+  if [[ "${CASAN_PROFILE:-}" == "prod" || "${CASAN_VERIFY_STRICT:-}" == "1" ]]; then
+    MISSING=""
+    [[ -f "$HEAD_FILE" ]] || MISSING="$MISSING head-file"
+    [[ -f "$HEAD_SIG" ]] || MISSING="$MISSING head-sig"
+    [[ -f "$AUDIT_PUB" ]] || MISSING="$MISSING pubkey"
+    command -v openssl >/dev/null 2>&1 || MISSING="$MISSING openssl"
+    echo "TOOL_AUDIT_UNSIGNED_STRICT_FAIL last_hash=$COMPUTED_HEAD missing=${MISSING# }" >&2
+    exit 1
+  fi
+  echo "TOOL_AUDIT_VALID anchor=unsigned last_hash=$COMPUTED_HEAD"
+fi