[Edge-Case] [P3] Non-standard/unhandled HTTP status codes render raw error pages 
without user-friendly messaging

**Severity:** P3 (Low)

**Issue Type:** Edge Case

**Frequency:** Everytime

**Environment:**
- Browser: Firefox 128 / Linux (Artix)
- OS: Artix Linux, x86_64
- URL: https://the-internet.herokuapp.com/status_codes

**Steps to Reproduce:**
1. Navigate to https://the-internet.herokuapp.com/status_codes
2. Click the "404" link — observe raw "Not Found" error text
3. Click the "500" link — observe raw "Internal Server Error" text
4. Manually navigate to /status_codes/1000 — observe unhandled response

**Expected:** Error pages should display user-friendly messages with navigation 
options (e.g. "Page not found. Return to homepage."). Non-standard codes should 
be caught and handled gracefully.

**Actual:** All error status codes (404, 500, and non-standard codes like 1000) 
render server error text with "Heroku" branding, yet no navigation links, and
no guidance for the user to recover. Non-standard codes are not caught by any 
fallback handler.

**Severity:** P3 — No data loss, but poor user experience. Users encountering 
errors have no path back into the application.