Parse chat mode shortcuts server-side

[RANGROO]

Summary

• parse validated one-shot chat symbols in HerikaServer
• strip shortcut wrappers and apply request-local modes without changing the saved CHIM mode
• require the plugin's boolean chat_shortcut_routed marker before parsing raw symbols
• ignore client-provided execution_mode values so the server is the only mode authority
• keep the Director shortcut request-local instead of resetting the saved mode to Standard

Paired change

• Requires Dwemer-Dynamics/CHIM#133

Validation

• PHP syntax checks passed for all five changed files
• focused PHPUnit suite passed: 55 tests, 127 assertions
• git diff --check passed

Review note

• The unstable push guard found file overlap with Complete Skyrim Oghma retrieval, catalogs, knowledge, and UI #701 in main.php. This branch is isolated and should be reviewed for integration order.

Limits

• Not deployed
• Not tested in game
• Director and Event Inject external side effects were not invoked by local runtime probes