fix(#2003): address code+security review findings

- warn (don't silently ignore) when --runtime is an unknown runtime that
  canonicalizeRuntimeName rejects; the warning surfaces via warnings[] so a
  typo like --runtime cluade or a runtime known to runtime-homes but not the
  alias manifest (e.g. grok) no longer silently resolves to the persisted
  runtime's config dir on this diagnostic command [M-1]
- add end-to-end CLI test for loop render-hooks --runtime (the exact command
  the bug report calls out as silently no-op'ing) [L-2]
- add closed-vocabulary rejection test: crafted --runtime values
  (../../etc/passwd, __proto__, --config-dir, garbage) are rejected, warn,
  and fall through to the persisted runtime — pins the security-load-bearing
  contract [NIT-01]
- add boundary tests: --config-dir wins over --runtime (precedence); missing
  --runtime value errors with USAGE [N-1]

Both orthogonal reviews returned APPROVE with no Critical/High findings.
Security review confirmed --runtime cannot coerce getGlobalConfigDir into an
arbitrary path (closed-vocabulary Map lookup + registry hash-key gate) and
does not expand the trust surface beyond the existing operator-controlled
--config-dir flag.

src/capability-state.cts

@@ -477,6 +477,16 @@ function resolveCapabilityRuntimeState(
         const canonical = runtimeNamePolicy.canonicalizeRuntimeName(runtimeOverride);
         if (canonical) {
           resolvedConfigDir = runtimeHomes.getGlobalConfigDir(canonical);
+        } else {
+          // #2003: unknown runtime override — warn (don't silently ignore the
+          // explicit input) and fall through to persisted-runtime resolution.
+          // Avoids a silent-wrong-result on this diagnostic command for typos
+          // (e.g. "cluade") or runtimes known to runtime-homes but not yet to
+          // the alias manifest (e.g. "grok"). The warning surfaces via the
+          // `warnings[]` channel consumed by cmdCapabilityState/cmdLoopRenderHooks.
+          warnings.push(
+            `--runtime "${runtimeOverride}" is not a known runtime; falling back to auto-detected/persisted runtime resolution`,
+          );
         }
       }
       if (!resolvedConfigDir) {