fix(symbian): normalize E7 letter keys

[doodlewind]

What changed

• normalize Qt/S60 lowercase ASCII letter keysyms before PocketJS button/native-key mapping
• apply the same normalization to key press and release events
• keep Qt special keys, punctuation, Unicode, and Fn-generated secondary characters unchanged
• add a C/C++98-compatible runtime helper and compile-time regression fixture
• pin the new runtime header in the Symbian qmake and npm package surfaces

Root cause

Qt 4.7's Symbian backend forwards ordinary character keysyms directly. On the Nokia E7, an unshifted physical W arrives as lowercase ASCII w, while the PocketJS host only matched uppercase Qt::Key_W (and likewise for A/S/D/R/E). Special keys such as Enter, Backspace, and arrows use Qt's special-key translation and therefore continued to work.

Impact

Unshifted E7 letter controls now reach native extensions and standard PocketJS button mappings. This restores OpenStrike WASD movement, R reload, and E fire without adding application-specific handling.

Validation

• bunx tsc --noEmit
• bun test tests/symbian-runtime.test.ts (14/14)
• bun test tests/npm-package.test.ts (3/3)
• git diff --check
• host C++98 compile
• pinned GCCE arm-none-symbianelf-g++ -std=gnu++98 -Werror compile
• independent review: no P0-P2 findings

Real-device verification will follow through the OpenStrike 0.3.1 package before this PocketJS target's hardware acceptance is closed.