Fix sandbox literal hit double counting

[minto-dane]

Motivation

• Literal sequence matches were being counted twice because the detector passed total_count (which includes sequence_hits) into the sandbox, and the sandbox also independently counts literal oo/おお/オオ sequences. This could turn single-match inputs that should only get a reaction into outbound SendMessage actions.
• The response compiler chose send-vs-react based on the untrusted sandbox proposal before capping repeats to the trusted detector count, enabling an inflated proposal to override the trusted detector.

Description

• Change DetectionReport::backend_count_for_sandbox() to return kanji_hits instead of total_count so only morphological/kanji hits (not configured literal sequence hits) are supplied to the sandbox (src/domain/detector.rs).
• Update proposal_to_action so the SendStamped branch computes repeats = (*count as usize).min(detector_total_count.max(1)) first and then decides react-vs-send based on repeats <= 1, ensuring the trusted detector count caps the outbound/send decision (src/security/response_compiler.rs).
• Add unit/regression tests: sandbox_backend_count_excludes_literal_sequence_hits for the detector sandbox count, caps_send_decision_to_trusted_detector_count for the compiler capping, and single_literal_match_reacts_once in the integration tests to assert governed behavior for a single literal match (src/domain/detector.rs, src/security/response_compiler.rs, tests/runtime_protection_integration.rs).

Testing

• Ran the new detector unit test sandbox_backend_count_excludes_literal_sequence_hits with DOCS_RS=1 and it passed.
• Ran the new response-compiler unit test caps_send_decision_to_trusted_detector_count with DOCS_RS=1 and it passed.
• Ran the new integration test single_literal_match_reacts_once with DOCS_RS=1 and it passed.
• cargo fmt --check and repository checks (git diff --check) passed.
• Note: running the full runtime_protection_integration test suite without DOCS_RS=1 failed earlier because the lindera-ipadic build script could not download dictionary assets in this environment; targeted tests were executed with DOCS_RS=1 to avoid that external download and validate the fixes.

---

Codex Task