feat(arsenal): parse scanner JSON into structured findings (#42)

The generic adapter factory returned raw stdout only (`adapter-tools.ts` success
path), so 35 catalogued scanners with `parserStatus: 'planned'` never populated the
structured `ToolResult.findings` channel — their output was dropped on the floor and
the agent could neither verify nor chain on it. The whole downstream pipe already
exists and is honest-by-construction: the agent loop stamps `provenance:'tool'` + the
raw output, the operator materialises each finding with output-evidence, and the live
gate (`evidence/gate.ts`) marks it verified.

Add `src/arsenal/parsers.ts` — `parseToolOutput(toolId, rawStdout) → ToolFinding[]`
for the five scanners that already emit machine-readable JSON via their existing arg
templates (zero template changes): nuclei (-jsonl), httpx (-json), dalfox (--format
json), ffuf (-of json), katana (-jsonl). Parsers are pure, dependency-free, and NEVER
throw: empty/garbled/unknown input yields `[]`, never a fabricated finding (same
discipline as stub-honesty / no-phantom-tools). The factory attaches parsed findings
while ALWAYS keeping the raw stdout as `output` — the evidence of record the gate checks.

- nuclei/dalfox emit CWE, which the tool channel dropped: add optional `cwe?: string[]`
  to `ToolFinding` and thread it through the operator's finding materialisation.
- flip `parserStatus: 'planned' → 'structured'` for httpx, dalfox, katana (nuclei/ffuf
  were already structured).

Adds `src/__tests__/parsers.test.ts` + fixtures: per-scanner field mapping, the
honesty contract (empty/garbled/adversarial → [], no throw), a factory-wiring check
that a minted adapter returns findings while preserving raw stdout, and an end-to-end
assertion that every parsed finding PASSES `gateLiveFinding` with provenance='tool'.

The minted-adapter path is gated behind T3MP3ST_FULL_ARSENAL, so the benchmarked
default arsenal is untouched. Supply-chain JSON tools (semgrep/gitleaks/trivy/grype)
and secret scanners (need redaction) are a clean follow-up.

src/arsenal/adapter-tools.ts

@@ -25,6 +25,7 @@
 
 import type { ToolAdapter } from './catalog.js';
 import type { CustomTool, ToolContext, ToolResult } from '../types/index.js';
+import { parseToolOutput } from './parsers.js';
 
 // =============================================================================
 // INJECTED DEPENDENCIES
@@ -470,7 +471,16 @@ export function adapterToCustomTool(adapter: ToolAdapter, deps: AdapterToolDeps)
       };
     }
 
-    return { success: true, output: result.stdout };
+    // Populate the structured `findings` channel from the raw stdout when a parser is wired for
+    // this tool (parseToolOutput → [] otherwise). The raw stdout is ALWAYS kept as `output` — it
+    // is the evidence of record the agent loop stamps onto each finding and the live gate checks;
+    // the parser summarises it, never replaces it. A parse yielding nothing leaves findings unset.
+    const findings = parseToolOutput(adapter.id, result.stdout);
+    return {
+      success: true,
+      output: result.stdout,
+      ...(findings.length ? { findings } : {}),
+    };
   };
 
   return {