fix(portals)!: reject unknown flags in all six CLIs

Silently discarded flags produced silently wrong results: jobdanmark
with --query (its real flag is --text) returned all 13,862 jobs as if
they matched, exit 0, empty stderr - indistinguishable from a real
result set. The four bunli CLIs get an argv preflight built from each
command's own options object; linkedin and freehire validate parsed
flags against per-command known sets. help/version still pass, and
add-portal.md's existing bogus-flag-exits-1 contract now holds for the
reference implementations contributors copy. One linkedin pin updated:
"--jobage-minutes -5" now fails as UNKNOWN_FLAG (the stray -5 token)
rather than BAD_ARG - same loud-failure invariant, earlier gate. Review
finding F13 (2026-08-19), decision approved by Mads.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

.agents/skills/jobdanmark-search/cli/tests/cli-flag-validation.test.ts

@@ -72,3 +72,26 @@ describe("Jobdanmark CLI flag validation", () => {
     });
   });
 });
+
+
+describe("unknown flag rejection", () => {
+  // add-portal.md's contract: "a bogus flag or missing required arg exits 1
+  // with a JSON error on stderr". A silently discarded flag is worse than an
+  // error: on jobdanmark a wrong flag name returned the entire database
+  // (13,862 results) as if it matched the query (review finding F13,
+  // 2026-08-19). Rejection happens before dispatch, so these are network-free.
+  test("a bogus --flag exits 1 with a JSON error instead of being silently discarded", async () => {
+    const result = await runCLI(["search", "--text", "test", "--bogus-flag", "xyz"]);
+    expect(result.exitCode).toBe(1);
+    expect(result.stdout).toBe("");
+    const error = JSON.parse(result.stderr);
+    expect(error.code).toBe("UNKNOWN_FLAG");
+    expect(error.error).toContain("--bogus-flag");
+  });
+
+  test("--query (another portal's free-text flag) is rejected, not treated as no filter", async () => {
+    const result = await runCLI(["search", "--query", "test"]);
+    expect(result.exitCode).toBe(1);
+    expect(JSON.parse(result.stderr).code).toBe("UNKNOWN_FLAG");
+  });
+});