Change keyboard hotkeys from arrow keys to WASD

[Nitrino]

Summary

• Replace arrow key navigation with WASD keys for subtitle control
• A: previous subtitle (was ArrowLeft)
• D: next subtitle (was ArrowRight)
• S: replay current subtitle (was ArrowDown)

Test plan

• Build the extension with pnpm build
• Load extension in browser and test on a streaming service
• Verify A key moves to previous subtitle
• Verify D key moves to next subtitle
• Verify S key replays current subtitle
• Verify Alt+A and Alt+D work for force navigation

[claude]

Code Review - Issues Found

I found 2 critical bugs in this PR that will break the "next subtitle" functionality:

Issue 1: Typo in key code (line 13)

File: src/utils/keyboardHandler.ts, line 13
Problem: event.code === "KeyDdddd" should be "KeyD"
Impact: The D key will never be detected because "KeyDdddd" is not a valid KeyboardEvent code.
Fix: Change to "KeyD"

Reference:

easysubs/src/utils/keyboardHandler.ts

Lines 12 to 17 in 657f422

	}
	if (event.code === "KeyDdddd") {
	event.stopPropagation();
	if (event.type === "keydowndddd") {
	moveKeyPressed({ direction: "next", force: event.altKey });
	}

Issue 2: Typo in event type (line 15)

File: src/utils/keyboardHandler.ts, line 15
Problem: event.type === "keydowndddd" should be "keydown"
Impact: Even if the key code were fixed, the action will never trigger because "keydowndddd" is not a valid event type.
Fix: Change to "keydown"

Reference:

easysubs/src/utils/keyboardHandler.ts

Lines 12 to 17 in 657f422

	}
	if (event.code === "KeyDdddd") {
	event.stopPropagation();
	if (event.type === "keydowndddd") {
	moveKeyPressed({ direction: "next", force: event.altKey });
	}

Both typos must be fixed for the D key (next subtitle) hotkey to work.

[claude]

Code Review

Found 2 critical bugs in the keyboard handler implementation that prevent the D key from working:

Issue 1: Invalid keyboard event code (line 13)

Bug: event.code === "KeyDdddd" should be event.code === "KeyD"

Location: src/utils/keyboardHandler.ts:13

Impact: The D key (next subtitle) functionality will be completely broken. Pressing D will never match "KeyDdddd" - the correct keyboard event code is "KeyD".

CLAUDE.md Reference: Violates CLAUDE.md lines 66-70 which documents D - Next subtitle.

Suggested fix:

  if (event.code === "KeyD") {

---

Issue 2: Invalid event type (line 15)

Bug: event.type === "keydowndddd" should be event.type === "keydown"

Location: src/utils/keyboardHandler.ts:15

Impact: Even if the key code were correct, this condition will never be true. Valid keyboard event types are only "keydown", "keyup", or "keypress" - never "keydowndddd".

CLAUDE.md Reference: Violates CLAUDE.md lines 66-70 which documents D - Next subtitle.

Suggested fix:

    if (event.type === "keydown") {

---

Summary: Both bugs appear to be typos where extra characters (dddd) were accidentally added. The D key handler is completely non-functional and must be fixed before merging.