Move the code and terraform audits into the reviews plugin

Copy the standalone code-review and terraform-review skills into
plugins/reviews as audit-code and audit-terraform. The rename separates the
automated, linter-driven audits from the guided review-pr walkthrough that
already lived here.

Resolve bundled script paths through ${SKILL_DIR}, exported in a new step 0.
CLAUDE_PLUGIN_ROOT is not set in the Bash tool environment, so the obvious
substitution would have expanded to nothing and broken every collection
script invocation.

Replace the PLAN and DESIGN docs with READMEs written from the current
SKILL.md and scripts. The old docs had drifted badly: they named semgrep
where the code calls opengrep, scoped five review agents where there are
now eight, and predated Lua, PowerShell, and GitHub Actions support.

Add CONSISTENCY_NORMS to the audit-terraform agent inputs. The collection
script writes consistency_norms.json and the agent prompt declares it, but
SKILL.md never listed it, leaving the variable unsubstituted.

Drop the --ingest-verdicts instruction from both skills. review_stats.py
parses no arguments, so the ref-mode verdict template it told users to feed
back could never be read.

Point audit-terraform's smoke test at README.md and resolve its fixture
paths relative to the test file rather than an absolute home directory.

Tests: 197 passing (audit-code), 106 passing (audit-terraform).

plugins/reviews/skills/audit-code/tests/test_adapter_psscriptanalyzer.py

@@ -0,0 +1,78 @@
+from pathlib import Path
+
+from scripts.adapters.psscriptanalyzer import parse_psscriptanalyzer_output
+
+
+_FIXTURES = Path(__file__).parent / "fixtures"
+_REPO = "/repo"
+
+
+def _pssa():
+    payload = (_FIXTURES / "psscriptanalyzer_sample.json").read_text()
+    return {f.rule_id: f for f in parse_psscriptanalyzer_output(payload, repo_root=_REPO)}
+
+
+def _injection():
+    payload = (_FIXTURES / "injectionhunter_sample.json").read_text()
+    return {
+        f.rule_id: f
+        for f in parse_psscriptanalyzer_output(payload, repo_root=_REPO, tool="injectionhunter")
+    }
+
+
+def test_paths_are_relative_to_repo_root():
+    f = _pssa()["PSAvoidUsingInvokeExpression"]
+    assert f.file == "scripts/Deploy.ps1"
+    assert f.tool == "psscriptanalyzer"
+
+
+def test_severity_mapping():
+    by_rule = _pssa()
+    assert by_rule["PSAvoidUsingConvertToSecureStringWithPlainText"].severity == "high"
+    assert by_rule["PSAvoidUsingInvokeExpression"].severity == "medium"
+    assert by_rule["PSUseDeclaredVarsMoreThanAssignments"].severity == "low"
+    assert by_rule["TypeNotFound"].severity == "critical"
+
+
+def test_line_range_from_extent():
+    f = _pssa()["PSAvoidUsingConvertToSecureStringWithPlainText"]
+    assert f.line == 20
+    assert f.end_line == 22
+
+
+def test_message_preserved():
+    assert "Invoke-Expression" in _pssa()["PSAvoidUsingInvokeExpression"].message
+
+
+def test_injectionhunter_findings_floor_at_high():
+    by_rule = _injection()
+    assert by_rule["InjectionRisk.InvokeExpression"].severity == "high"
+    assert by_rule["InjectionRisk.AddScriptBlock"].severity == "high"
+
+
+def test_injectionhunter_tool_name_and_location():
+    f = _injection()["InjectionRisk.AddScriptBlock"]
+    assert f.tool == "injectionhunter"
+    assert f.file == "scripts/Deploy.ps1"
+    assert f.line == 33
+    assert f.end_line == 35
+
+
+def test_single_object_not_array():
+    payload = '{"RuleName":"PSAvoidUsingWriteHost","Severity":"Warning","ScriptPath":"/repo/a.ps1","Line":3,"EndLine":3,"Message":"m"}'
+    findings = parse_psscriptanalyzer_output(payload, repo_root=_REPO)
+    assert len(findings) == 1
+    assert findings[0].file == "a.ps1"
+
+
+def test_handles_empty_array():
+    assert parse_psscriptanalyzer_output("[]", repo_root=_REPO) == []
+
+
+def test_handles_invalid_json():
+    assert parse_psscriptanalyzer_output("not json", repo_root=_REPO) == []
+
+
+def test_unknown_severity_defaults_to_medium():
+    payload = '[{"RuleName":"X","Severity":"Bogus","ScriptPath":"/repo/a.ps1","Line":1,"EndLine":1,"Message":"m"}]'
+    assert parse_psscriptanalyzer_output(payload, repo_root=_REPO)[0].severity == "medium"