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/path-guard.sh

@@ -0,0 +1,40 @@
+#!/usr/bin/env bash
+set -uo pipefail
+
+# CASAN Plan-16 SEC-28 (X-04) — path-traversal / symlink guard.
+#
+# A tool that takes a file path as input/output can be pointed at an arbitrary
+# location via `..` or a symlink (e.g. a symlink named "input.txt" -> /etc/passwd),
+# reading or writing outside the workspace. This resolves the REAL path (following
+# every symlink) and refuses anything that escapes the allowed root.
+#
+# Usage:  path-guard.sh <path> [allowed-root]     (default root: repo workspace)
+# Exit:   0 inside the root, 1 outside / unresolvable.
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+source "$SCRIPT_DIR/casan-paths.sh"
+PROJECT_ROOT="$CASAN_APP_ROOT"
+
+TARGET="${1:-}"
+ROOT="${2:-$PROJECT_ROOT}"
+if [[ -z "$TARGET" ]]; then
+  echo "Usage: path-guard.sh <path> [allowed-root]" >&2
+  exit 64
+fi
+
+python3 - "$TARGET" "$ROOT" <<'PY'
+import os
+import sys
+
+target, root = sys.argv[1], sys.argv[2]
+# realpath resolves symlinks in every existing path component and normalizes "..";
+# for a not-yet-created leaf it resolves the existing parent chain.
+real_target = os.path.realpath(target)
+real_root = os.path.realpath(root)
+
+if real_target == real_root or real_target.startswith(real_root + os.sep):
+    print(f"PATH_OK {real_target}")
+    sys.exit(0)
+sys.stderr.write(f"PATH_ESCAPES_ROOT target={target} real={real_target} root={real_root}\n")
+sys.exit(1)
+PY