Strengthen console controller tests

[WarLikeLaux]

Q	A
Is bugfix?	❌
New feature?	❌
Tests added?	✔️
Breaks BC?	❌
Fixed issues

What does this PR do?

Adds tests for console controllers (CacheController, FixtureController, HelpController, ServeController, MigrateController, BaseMigrateController) to cover previously untested code paths.

Coverage

File	Tests	Lines	MSI
CacheController.php	27	81/106 (76%) → 94/94 (100%)	87% (99/113)
FixtureController.php	51	0/188 (0%) → 169/171 (99%)	60% (155/256)
HelpController.php	9 → 36	225/269 (84%) → 251/252 (100%)	69% (321/460)
ServeController.php	5 → 8	41/45 (91%) → 37/40 (93%)	69% (39/56)
BaseMigrateController.php	+47	132/348 (38%) → 312/323 (97%)	N/A
MigrateController.php	+34	58/249 (23%) → 234/239 (98%)	N/A

CacheController and FixtureController had existing tests that required MySQL. New test classes (CacheControllerSqliteTest, FixtureControllerSqliteTest) test the same code without MySQL dependency, making them runnable in all CI environments.

MigrateController/BaseMigrateController MSI unavailable due to pre-existing test failures (template PHPDoc mismatch in testGenerateMigration, MySQL driver in testRefreshMigration#1).

Uncovered lines:

• FixtureController:159,235 - dead code (defensive checks after getFixturesConfig() which always throws before returning empty)
• HelpController:496 - dead branch ($type === null after trim((string)$type))
• ServeController:135-136 - isAddressTaken() true path (needs real open port); 141 - passthru() in runCommand()
• BaseMigrateController:488,490 - YII_ENV_PROD constant branch; 681,683 - file_put_contents failure; 815-823,975,998 - methods overridden in MigrateController
• MigrateController:313-314,328 - FK dropping / non-view error (SQLite doesn't support DROP FOREIGN KEY); 491-492 - dead code (ReflectionException never thrown, DI wraps it in InvalidConfigException)

Changelog not required, because no source files changed.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.52%. Comparing base (279108f) to head (5ea60d7).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #20792      +/-   ##
============================================
+ Coverage     78.68%   79.52%   +0.84%     
  Complexity    11566    11566              
============================================
  Files           376      376              
  Lines         30748    30748              
============================================
+ Hits          24194    24453     +259     
+ Misses         6554     6295     -259     

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