fix: NaN filter bypass in LinkedIn CLI --jobage/--page/--limit flags (#35)

* fix: silent zero output in salary converter and NaN filter bypass in LinkedIn CLI

Bug #10 (convert_salary_excel.py):
openpyxl ws[row_index] random access fails silently under read_only=True,
leaving headers empty and producing no output. Fix: save the header row
values during the existing iter_rows scan so ws[header_row] is never called.

Bug #5 (.agents/skills/linkedin-search/cli/src/cli.ts):
parseInt on --jobage/--page/--limit flags returns NaN on non-numeric input.
NaN propagates silently — the jobage filter is dropped, page/limit are broken.
Fix: validate each parsed int, exit 1 with a structured BAD_ARG error on NaN.

Also adds:
- tests/test_bug10_salary_converter.py: 10 scenarios, 31 assertions (all green)
- tests/test_bug5_linkedin_cli.sh: 8 scenarios, 16 assertions (all green)
- docs/bugfixes.md: root cause, impact, and fix explanation for both bugs,
  plus a note on the pre-existing detect_column_type "n" pattern issue

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* fix: address PR review — drop salary converter change, move test to bun

- Drop tools/convert_salary_excel.py change (bug not reproducible on
  modern openpyxl; reviewer confirmed master works correctly)
- Drop tests/test_bug10_salary_converter.py and top-level tests/ dir
- Drop docs/bugfixes.md (analysis belongs in PR description, not repo)
- Replace tests/test_bug5_linkedin_cli.sh with a proper bun test file
  at .agents/skills/linkedin-search/cli/tests/cli-flag-validation.test.ts
  following the jobindex-search/cli/tests/ convention (runCLI/parseJSON
  helpers, describe/test/expect, descriptive names)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

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

@@ -0,0 +1,86 @@
+import { describe, test, expect } from "bun:test";
+import { runCLI } from "./helpers";
+
+const LOCATION = "Copenhagen, Denmark";
+
+function parsedStderr(stderr: string): { error?: string; code?: string } {
+  try {
+    return JSON.parse(stderr);
+  } catch {
+    return {};
+  }
+}
+
+describe("LinkedIn CLI flag validation", () => {
+  describe("--jobage NaN validation", () => {
+    test("non-numeric string exits 1 with BAD_ARG", async () => {
+      const result = await runCLI(["search", "-l", LOCATION, "--jobage", "foo"]);
+      expect(result.exitCode).not.toBe(0);
+      const err = parsedStderr(result.stderr);
+      expect(err.code).toBe("BAD_ARG");
+      expect(err.error).toMatch(/jobage/);
+    });
+
+    test("boolean flag (no value) exits 1 with BAD_ARG", async () => {
+      const result = await runCLI(["search", "-l", LOCATION, "--jobage"]);
+      expect(result.exitCode).not.toBe(0);
+      expect(result.stderr).toBeTruthy();
+    });
+
+    test("valid integer passes validation", async () => {
+      const result = await runCLI(["search", "-l", LOCATION, "--jobage", "7", "--limit", "1"]);
+      const err = parsedStderr(result.stderr);
+      expect(err.code).not.toBe("BAD_ARG");
+    });
+
+    test("float string truncated to integer, no error", async () => {
+      // parseInt("7.5") = 7, which is valid
+      const result = await runCLI(["search", "-l", LOCATION, "--jobage", "7.5", "--limit", "1"]);
+      const err = parsedStderr(result.stderr);
+      expect(err.code).not.toBe("BAD_ARG");
+    });
+
+    test("zero is accepted (falsy int should not be treated as missing)", async () => {
+      const result = await runCLI(["search", "-l", LOCATION, "--jobage", "0", "--limit", "1"]);
+      const err = parsedStderr(result.stderr);
+      expect(err.code).not.toBe("BAD_ARG");
+    });
+  });
+
+  describe("--page NaN validation", () => {
+    test("non-numeric string exits 1 with BAD_ARG", async () => {
+      const result = await runCLI(["search", "-l", LOCATION, "--page", "abc"]);
+      expect(result.exitCode).not.toBe(0);
+      const err = parsedStderr(result.stderr);
+      expect(err.code).toBe("BAD_ARG");
+      expect(err.error).toMatch(/page/);
+    });
+  });
+
+  describe("--limit NaN validation", () => {
+    test("non-numeric string exits 1 with BAD_ARG", async () => {
+      const result = await runCLI(["search", "-l", LOCATION, "--limit", "xyz"]);
+      expect(result.exitCode).not.toBe(0);
+      const err = parsedStderr(result.stderr);
+      expect(err.code).toBe("BAD_ARG");
+      expect(err.error).toMatch(/limit/);
+    });
+  });
+
+  describe("existing validations (regression)", () => {
+    test("missing --location exits 1 with NO_LOCATION", async () => {
+      const result = await runCLI(["search"]);
+      expect(result.exitCode).not.toBe(0);
+      const err = parsedStderr(result.stderr);
+      expect(err.code).toBe("NO_LOCATION");
+    });
+
+    test("all valid flags produce no BAD_ARG", async () => {
+      const result = await runCLI([
+        "search", "-l", LOCATION, "--jobage", "7", "--page", "1", "--limit", "5",
+      ]);
+      const err = parsedStderr(result.stderr);
+      expect(err.code).not.toBe("BAD_ARG");
+    });
+  });
+});