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The Site job fails when the data file is out of date or a page asks for a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

@@ -1,3 +1,4 @@
+#include "app_keys.h"
 #include "file_viewer.h"
 
 #include <Arduino.h>
@@ -266,27 +267,15 @@ void FileViewer::openPacket(int index) {
 }
 
 void FileViewer::help(std::vector<KeyHelp>& out) const {
-    if (confirm_) return help::dialog(out);
+    if (confirm_) return keys::add(out, keys::kDialog);
     switch (mode_) {
-        case Mode::Packet:
-            out.push_back({"; .", "scroll"});
-            out.push_back({"Enter", "back to the packets"});
-            return;
-        case Mode::Text:
-        case Mode::Hex:
-            out.push_back({"; .", "a line up, down"});
-            out.push_back({", /", "a page up, down"});
-            out.push_back({"t  b", "the top, the end"});
-            if (mode_ == Mode::Text) out.push_back({"e", "edit it (up to 16 KB)"});
-            break;
-        case Mode::Pcap:
-            help::list(out, "the packet");
-            out.push_back({", /", "a page up, down"});
-            break;
-        case Mode::Ota: out.push_back({"Enter", "install it, if it's genuine"}); break;
-        case Mode::Gpx: break;
+        case Mode::Text: keys::add(out, keys::kViewerText); break;
+        case Mode::Hex: keys::add(out, keys::kViewerHex); break;
+        case Mode::Pcap: keys::add(out, keys::kViewerPcap); break;
+        case Mode::Packet: keys::add(out, keys::kViewerPacket); break;
+        case Mode::Gpx: keys::add(out, keys::kViewerGpx); break;
+        case Mode::Ota: keys::add(out, keys::kViewerOta); break;
     }
-    out.push_back({"Tab", mode_ != base_ ? "back to the file's own view" : base_ == Mode::Hex || base_ == Mode::Gpx ? "the file as text" : "the file as hex"});
 }
 
 bool FileViewer::onKey(const KeyEvent& e) {