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/tests/phase-sec12-tests.sh

@@ -0,0 +1,55 @@
+#!/usr/bin/env bash
+set -uo pipefail
+
+# CASAN Plan-16 SEC-12 — drift-detect semantic invariants (beyond char-similarity).
+#
+# Char-similarity alone misses a SEMANTIC inversion: dropping a negation
+# ("must NOT deploy" -> "must deploy") keeps similarity ~0.97 but flips the meaning,
+# and previously passed. Now a candidate that removes negations present in the
+# golden, or that drops a must-keep invariant, FAILS. Proves the flip is caught and
+# identical/benign content still passes.
+#
+# Deterministic; hermetic.
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+source "$SCRIPT_DIR/../scripts/bash/casan-paths.sh"
+PROJECT_ROOT="$CASAN_APP_ROOT"
+DD="$CASAN_HARNESS_ROOT/scripts/bash/drift-detect.sh"
+WORK="$(mktemp -d)"
+trap 'rm -rf "$WORK"' EXIT
+
+PASS=0; FAIL=0
+pass() { echo "PASS: $1"; PASS=$((PASS + 1)); }
+fail() { echo "FAIL: $1"; FAIL=$((FAIL + 1)); }
+rc_of() { set +e; "$@" >/dev/null 2>&1; echo $?; set -e 2>/dev/null || true; }
+
+echo "===== Plan-16 SEC-12: drift semantic invariants ====="
+
+printf 'You MUST NOT deploy to production without explicit human approval.\n' > "$WORK/golden.txt"
+printf 'You MUST deploy to production without explicit human approval.\n' > "$WORK/flip.txt"
+cp "$WORK/golden.txt" "$WORK/same.txt"
+
+# Negation flip: near-identical text (similarity ~0.97) but a "NOT" vanished.
+[[ "$(rc_of bash "$DD" "$WORK/golden.txt" "$WORK/flip.txt" "$WORK/r1.json")" -ne 0 ]] \
+  && pass "negation flip FAILS despite high similarity" \
+  || fail "negation flip passed (semantic inversion missed)"
+grep -q 'negation_dropped' "$WORK/r1.json" \
+  && pass "report records the negation_dropped reason" || fail "reason not recorded"
+
+# Identical golden/candidate still passes.
+[[ "$(rc_of bash "$DD" "$WORK/golden.txt" "$WORK/same.txt" "$WORK/r2.json")" -eq 0 ]] \
+  && pass "identical content passes (no false positive)" || fail "identical content flagged"
+
+# must-keep invariant missing from candidate → FAIL.
+printf 'MUST NOT deploy\n' > "$WORK/mustkeep.txt"
+[[ "$(rc_of env CASAN_DRIFT_MUSTKEEP_FILE="$WORK/mustkeep.txt" bash "$DD" "$WORK/golden.txt" "$WORK/flip.txt" "$WORK/r3.json")" -ne 0 ]] \
+  && pass "missing must-keep invariant FAILS" || fail "missing must-keep not detected"
+
+# must-keep invariant present → pass.
+printf 'production\n' > "$WORK/mustkeep2.txt"
+[[ "$(rc_of env CASAN_DRIFT_MUSTKEEP_FILE="$WORK/mustkeep2.txt" bash "$DD" "$WORK/golden.txt" "$WORK/same.txt" "$WORK/r4.json")" -eq 0 ]] \
+  && pass "present must-keep invariant passes" || fail "present must-keep wrongly failed"
+
+echo ""
+echo "===== SEC-12 SUMMARY: PASS=$PASS FAIL=$FAIL ====="
+[[ "$FAIL" -eq 0 ]] || exit 1