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/src/cli.ts

@@ -83,6 +83,32 @@ async function main(): Promise<number> {
       return 1
     }
     const fmt = (flags.format as string) || "json"
+
+    const parseIntFlag = (name: string, raw: string | boolean | string[]): number | null => {
+      const val = parseInt(raw as string, 10)
+      if (isNaN(val)) {
+        process.stderr.write(JSON.stringify({ error: `--${name} must be a number, got "${raw}"`, code: "BAD_ARG" }) + "\n")
+        return null
+      }
+      return val
+    }
+
+    if (flags.jobage !== undefined) {
+      const v = parseIntFlag("jobage", flags.jobage)
+      if (v === null) return 1
+      flags.jobage = String(v)
+    }
+    if (flags.page !== undefined) {
+      const v = parseIntFlag("page", flags.page)
+      if (v === null) return 1
+      flags.page = String(v)
+    }
+    if (flags.limit !== undefined) {
+      const v = parseIntFlag("limit", flags.limit)
+      if (v === null) return 1
+      flags.limit = String(v)
+    }
+
     const opts: SearchOpts = {
       query: typeof flags.query === "string" ? flags.query : undefined,
       location,