fix: resilient modal button detection and form filler robustness

easy_apply.mjs:
- findModalButton() uses 3-strategy detection: aria-label exact/substring,
  then exact button text match — survives LinkedIn aria-label changes
- Check order fixed: Next → Review → Submit (submit only when no forward nav)
- All queries scoped to modal + :not([disabled])
- dismissModal() with fallback chain: Dismiss → Close/X → Escape → Discard
- Uses innerText for button text (ignores hidden children)

form_filler.mjs:
- All queries scoped to container (modal when present, page otherwise)
- Radio labels use $$('label') + textContent instead of broken :has-text()
- Autocomplete uses waitForSelector instead of blind 800ms sleep
- EEO selects iterate options directly (selectOption doesn't accept regex)
- Country code check ordered before country to prevent fragile match order

constants.mjs:
- Add AUTOCOMPLETE_WAIT, AUTOCOMPLETE_TIMEOUT
- Remove unused button selectors (now handled inline by findModalButton)

ai_answer.mjs + keywords.mjs:
- Use ANTHROPIC_API_URL constant, claude-sonnet-4-6 model

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

lib/keywords.mjs

@@ -48,7 +48,7 @@ Example format: ["query one", "query two", "query three"]`;
       'anthropic-version': '2023-06-01'
     },
     body: JSON.stringify({
-      model: 'claude-haiku-4-5-20251001',
+      model: 'claude-sonnet-4-6-20251101',
       max_tokens: 1024,
       messages: [{ role: 'user', content: prompt }]
     })