chore(release): bump llm-security to v7.1.0

Closes A4 of v7.1.0 critical-review patch — release artefacts.

- Version bump 7.0.0 → 7.1.0 across active version sources:
  * package.json
  * .claude-plugin/plugin.json
  * CLAUDE.md header
  * README.md badge
  * scanners/ide-extension-scanner.mjs (VERSION constant)
  * marketplace root README plugin entry
- Marketplace root README test count: 1487 → 1511.
- CHANGELOG.md: new [7.1.0] - 2026-04-29 section above [7.0.0],
  documenting B1, B2, B4, B8, honesty-sweep (7 phrases), and
  test-count delta (+24 → 1511 total).
- docs/security-hardening-guide.md: §6 last-updated bump + new
  v7.1.0 calibration note on hook-level fixes (pathguard regex
  hole, distributed-trifecta block-mode bypass).

Historical references to "7.0.0" intentionally preserved in:
- CHANGELOG [7.0.0] entries (history)
- README.md version-history table v5.0.0/v7.0.0 rows (history)
- CLAUDE.md §"v7.0.0 — Severity-dominated risk scoring" (describes
  what changed at v7.0.0 release)
- scanners/ JSDoc comments noting "v7.0.0+" formula provenance
- agents/ + tests/ + knowledge/ provenance comments

Pre-existing untracked/modified tracker noise (.gitignore,
marketplace.json, config-audit/docs, ultraplan-local/docs) is not
part of this commit per the v7.1.0 NEXT-SESSION-PROMPT handoff.

Tests: 1511/1511 green.

plugins/llm-security/README.md

@@ -6,7 +6,7 @@
 
 *AI-generated: all code produced by Claude Code through dialog-driven development. [Full disclosure →](../../README.md#ai-generated-code-disclosure)*
 
-![Version](https://img.shields.io/badge/version-7.0.0-blue)
+![Version](https://img.shields.io/badge/version-7.1.0-blue)
 ![Platform](https://img.shields.io/badge/platform-Claude_Code_Plugin-purple)
 ![Agents](https://img.shields.io/badge/agents-6-orange)
 ![Scanners](https://img.shields.io/badge/scanners-22-cyan)