Work through the 1.0 milestone: focus, backend tests, remote, login code

#20 Each settings column is a focus group now. The middle column is shorter
than the left, so "down" past its last row used to search wider and land
back in the left column — "Erweitert" was only reachable by going right,
down, left.

#22 The whole backend path had no coverage, which is why an afternoon
against the real instance found three bugs. Parsing moved out of
DispatcharrRepository into DispatcharrJson and is covered by twelve tests
built from the shapes that instance actually returns: pagination, channels
without a uuid or hidden from output, effective vs plain names and logos,
favourites without the key, inactive output profiles, and all three EPG
envelopes the fork has shipped. Android's stub org.json throws in unit
tests, so the real implementation is on the test classpath.
What no test can reach is written down in tests/dispatcharr-checkliste.md.

#24 The remote's channel tab was only ever read in source. Driven through
the DevTools protocol against the real backend it lists 503 channels with
logos and EPG, the search filters, the club chip switches view, and a star
survives the round trip to the backend and back — set and unset. It also
showed the phone still spelling out "BL: Bayer Leverkusen - VfB Stuttgart,
tipico Topspiel der Woche, 16. Spieltag" where the TV shortens to the
fixture; the payload shortens now too.

#23 The TV says "Der alte Code war abgelaufen — neuer Code 566071643"
instead of swapping the digits without a word.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

app/build.gradle.kts

@@ -97,6 +97,9 @@ dependencies {
     implementation("com.google.zxing:core:3.5.3")
     implementation("io.coil-kt:coil-compose:2.7.0")
     testImplementation("junit:junit:4.13.2")
+    // Android ships a stub org.json for unit tests that throws on every call;
+    // the real one lets the backend parsing be tested without a device.
+    testImplementation("org.json:json:20240303")
 }
 
 // Full JDK for javac via toolchain (host may only have a JRE); resolved by