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The Site job fails when the data file is out of date or a page asks for a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/launcher_app.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include "app.h"
+#include "app_keys.h"
 #include "app_manager.h"
 #include "list_model.h"
 #include "ui/theme.h"
@@ -14,7 +15,7 @@ class LauncherApp : public App {
     void onEnter() override;
     bool onKey(const KeyEvent& e) override;
     void draw(Canvas& c) override;
-    void help(std::vector<KeyHelp>& out) const override { help::list(out, "open the App"); }
+    void help(std::vector<KeyHelp>& out) const override { keys::add(out, keys::kLauncher); }
 
    private:
     AppManager* manager_ = nullptr;