PHP configuration requirements for installer warnings (Issue #484)

Issue: https://github.com/sebiboga/testlink-upgraded/issues/484 Fix commit: c8e6edd14 on branch fix/issue-484-php-config-installer-warnings

Symptom

install/installCheck.php (Web and PHP configuration table) warned on every dev environment started with the previously documented bare php -S command:

tab-warning'>24 minutes and 0 seconds - (Short. Consider to extend.)
tab-warning'>30 seconds - We suggest 120 seconds in order to manage hundred of test cases (edit php.ini)
tab-warning'>-1 MegaBytes - We suggest 64 MB in order to manage hundred of test cases

The third one was a false positive: -1 is PHP's unlimited sentinel.

Required settings

Setting	Required	Why
max_execution_time	120	Large test-case operations (import/export, bulk edits)
session.gc_maxlifetime	2880	48-minute idle timeout; installer requires > 30 min
memory_limit	64M	Minimum recommended for hundred of test cases

The fix

1. Launcher — new scripts/devserver.sh starts the built-in server with all three values applied via -d flags:

scripts/devserver.sh 8082     # kills the port first, docroot = repo root

2. README — Quick Start (Development) now uses the launcher and lists the php.ini equivalents for real web servers:

max_execution_time = 120
session.gc_maxlifetime = 2880
memory_limit = 64M

3. Checker correctness — lib/functions/configCheck.php check_php_settings() now understands PHP's sentinels:
   • max_execution_time = 0 → OK (no limit) (no time limit);
   • memory_limit = -1 → OK (unlimited). Genuine under-provisioning still warns exactly as before.

Verification

• Pre-fix curl reproduced all three warnings; post-fix (server restarted via launcher) all rows are green:
  • 48 minutes and 0 seconds - (OK)
  • OK (120 seconds)
  • OK (64 MegaBytes)
• Sentinel paths verified in isolation (OK (unlimited) / OK (no limit)).
• Login + main shell regression OK; events table: no new Error/Warning.

Regression suite: Suite 484 in tmp/TLU_Test_Cases.md (9/9 PASS).