[Server/Client/Protocol] Address developer role review feedback

Address ZeizaZach's review of the developer staff role:

- Nudge the developer log query to exclude private chat and sender IPs
  (the ModeratorCommand path still sees everything).
- Deduplicate Command_GetLogHistory into Command_ViewLogHistory, which now
  extends both ModeratorCommand (ext) and DeveloperCommand (dev_ext); the
  client picks the DeveloperCommand-scoped extension by extendee, and the
  server reads it via the extension number.
- Pull the uptime snapshot SQL into Servatrice_DatabaseInterface as
  getLatestUptimeSnapshot() and widen the reported counters to 64-bit.
- Document the admin bitfield (1 admin, 2 moderator, 4 judge, 8 developer)
  and add a server-side test for the developer command path.

servatrice/servatrice.sql

@@ -25,6 +25,9 @@ INSERT INTO cockatrice_schema_version VALUES(36);
 -- users and user data tables
 CREATE TABLE IF NOT EXISTS `cockatrice_users` (
   `id` int(7) unsigned zerofill NOT NULL auto_increment,
+  -- Bitfield of staff levels: 1 = admin (implies moderator), 2 = moderator,
+  -- 4 = judge, 8 = developer. Operators set these by hand with
+  -- "UPDATE cockatrice_users SET admin = ...".
   `admin` tinyint(1) NOT NULL,
   `name` varchar(35) NOT NULL,
   `realname` varchar(255) NOT NULL,