fix(release): ship prebuilt assets and bump fallback version

Two release-blocking bugs traced to the same root cause: the unanchored
`data/` rule in .gitignore matched server/src/ledgrab/data/, which is
where shipped package assets live (prebuilt sounds, game adapters).
The files were never `git add`-able without -f, so they never reached
the v0.4.2 tag and CI builds couldn't include them.

- .gitignore: anchor /data/ and /server/data/ so nested package data
  dirs are not ignored.
- Track previously-excluded shipped assets:
  - server/src/ledgrab/data/prebuilt_sounds/{alert,bell,chime,ping,pop}.wav
  - server/src/ledgrab/data/game_adapters/{minecraft,rocket_league,valorant}.yaml
- Bump _FALLBACK_VERSION 0.3.0 -> 0.4.2 to match pyproject.toml.
  The Windows installer strips ledgrab-*.dist-info, so
  importlib.metadata falls back to this literal — which is why
  v0.4.2 reports v0.3.0 in the WebUI.
- Patch _FALLBACK_VERSION at bundle time in build-common.sh and
  build-dist.ps1 so future drift is auto-corrected by the build.

build/build-dist.ps1

@@ -196,6 +196,17 @@ New-Item -ItemType Directory -Path (Join-Path $DistDir "logs") -Force | Out-Null
 Get-ChildItem -Path $srcDest -Recurse -Filter "*.map" | Remove-Item -Force -ErrorAction SilentlyContinue
 Get-ChildItem -Path $srcDest -Recurse -Directory -Filter "__pycache__" | Remove-Item -Recurse -Force -ErrorAction SilentlyContinue
 
+# Patch the fallback version in the bundled __init__.py so the WebUI always
+# reports the release version — the installer strips ledgrab-*.dist-info from
+# site-packages (above), so importlib.metadata falls back to this literal.
+$bundledInit = Join-Path $srcDest "ledgrab\__init__.py"
+if (Test-Path $bundledInit) {
+    $initContent = Get-Content $bundledInit -Raw
+    $patched = [regex]::Replace($initContent, '_FALLBACK_VERSION\s*=\s*"[^"]*"', "_FALLBACK_VERSION = `"$VersionClean`"")
+    Set-Content -Path $bundledInit -Value $patched -NoNewline
+    Write-Host "  Patched _FALLBACK_VERSION -> $VersionClean"
+}
+
 # ── Create launcher ────────────────────────────────────────────
 
 Write-Host "[8/8] Creating launcher..."