Keys: one table file for the device's help panel and the website's key tables (#72)

Every screen's keys are constant tables in lib/core/src/app_keys.h (52 of
them, each under an `// id: Title` comment). An App's help() picks the table
of the state it is in. site/tools/gen_dev_docs.py reads the same file and
writes site/data/keys.toml; the `keys` shortcode shows a screen's tables on
its guide page, and /guide/keys/ shows all of them.

The Site job fails when the data file is out of date or a page asks for a
table that doesn't exist, and now also runs when app_keys.h changes. A key
added to an App shows up on the website without anyone editing a page.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT

src/apps/setup_app.cpp

@@ -1,3 +1,4 @@
+#include "app_keys.h"
 #include "setup_app.h"
 
 #include "platform/identity.h"
@@ -47,16 +48,10 @@ bool SetupApp::onKey(const KeyEvent& e) {
 void SetupApp::help(std::vector<KeyHelp>& out) const {
     switch (wizard_.step()) {
         case Step::LongName:
-        case Step::ShortName: help::textEntry(out, "next step"); break;
+        case Step::ShortName: keys::add(out, keys::kSetupText); break;
         case Step::Region:
-        case Step::Timezone:
-            help::list(out, "choose it, next step");
-            out.push_back({"`", "the step before"});
-            break;
-        default:
-            out.push_back({"Enter", "continue"});
-            out.push_back({"`", "the step before"});
-            break;
+        case Step::Timezone: keys::add(out, keys::kSetupChoice); break;
+        default: keys::add(out, keys::kSetup); break;
     }
 }