Add global music player, invoicing/payment system, account subpages, mail account admin, and the qualityiron.vegas Jet 2.0 port

Jet interpreter (Tag.cpp, __call.cpp, __imap*.cpp/h, __smtpsend.cpp/h,
__imapemptyfolder.cpp/h - new): assorted parser/tag fixes found across
this work - a stray literal-tag-in-comment and backslash-quote parser
corruption class, a dangling-pointer fix, a __call.cpp fd leak, IMAP
folder-management tags, multi-account/per-host IMAP support, and a
smtpsend Message-ID fix.

barant.com site (jetc/barant-site/):
- A site-wide persistent music player (header band, playlist/queue,
  stereo FFT EQ, session-persisted state) fed by new library/
  ianslibrary/music song-list subpages.
- /account split into info/phones/invoices subpages; a full invoicing
  and Square payment system (create/edit/copy/pay/email invoice);
  admin invoice management and mail-account management subpages.
- /services split into overview/hosting/siptrunking/documents
  subpages, retiring the old standalone pages.
- SIPPHONE.tag: a Jet 2.0 WebRTC softphone tag.
- main.css/spa.js/email.js: the SPA loading indicator, the music
  player band styling, and assorted fixes accumulated alongside this
  work.

qualityiron-site/: the qualityiron.vegas job/contractor/customer/
document management app, ported from its original Jet 1.4 codebase to
Jet 2.0 as barant.coms APIServers second multi-tenant site.

wcwc/wcwc.jet: the WCWC site Jet source (wcwc.jtc build output not
included).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

__imapaccounts.h

@@ -11,8 +11,8 @@
 namespace jet {
 
    ///
-   /// <imapaccounts action="add|remove|getpassword|firstuser|list"
-   ///                list="$[@_imap_accounts]" user="..." password="...">
+   /// <imapaccounts action="add|remove|getpassword|gethost|firstuser|list"
+   ///                list="$[@_imap_accounts]" host="..." user="..." password="...">
    ///
    /// Pure list-transform tag (no session-variable access of its own,
    /// no IMAP connection) that manages the multi-account list webmail
@@ -23,34 +23,45 @@ namespace jet {
    /// touches Global's session-variable map directly).
    ///
    /// The list's own on-the-wire encoding (semicolon-separated
-   /// "base64(user):base64(password)" entries) is private to this tag -
-   /// callers only ever pass the whole `list` value back in verbatim
-   /// and use the returned value the same way, so the choice of
-   /// delimiter can't collide with any real username or password
-   /// character.
+   /// "base64(host):base64(user):base64(password)" entries) is private
+   /// to this tag - callers only ever pass the whole `list` value back
+   /// in verbatim and use the returned value the same way, so the
+   /// choice of delimiter can't collide with any real username or
+   /// password character. Each account can live on its own IMAP server
+   /// (see the <imap>/<imaplist>/etc. tags' own optional host/port
+   /// keywords), not just the one fixed host in email.cfg.
    ///
-   /// action="add": upserts user/password (removing any existing entry
-   /// for the same user first, so reconnecting with a changed password
-   /// updates it) - returns the updated encoded list.
+   /// action="add": upserts host/user/password (removing any existing
+   /// entry for the same user first, so reconnecting with a changed
+   /// password or server updates it) - returns the updated encoded list.
    /// action="remove": drops the entry for user, if present - returns
    /// the updated encoded list.
    /// action="getpassword": returns the stored password for user, or
    /// an empty string if not present.
+   /// action="gethost": returns the stored host for user, or an empty
+   /// string if not present.
    /// action="firstuser": returns the first entry's username, or an
    /// empty string if the list is empty.
    /// action="list": returns JSON ({"accounts":[...],"active":"..."})
    /// - the one client-facing action; "active" echoes the `active`
    /// keyword (typically $[@_imap_user]) back verbatim so the sidebar
-   /// can highlight the current one, and never includes any password.
+   /// can highlight the current one, and never includes any password or
+   /// host (unchanged shape from before per-account hosts existed -
+   /// nothing client-side needs the host to switch between already-
+   /// connected accounts).
    ///
    class __imapaccounts : public Tag {
 
+      struct Account {
+         std::string host, user, password;
+      };
+
     public:
       __imapaccounts(coreutils::ZString &in, coreutils::MString &parentOut, Global &global, Tag *parent, Tag *local);
 
     private:
-      static std::vector<std::pair<std::string, std::string>> decodeList(const std::string &encoded);
-      static std::string encodeList(const std::vector<std::pair<std::string, std::string>> &entries);
+      static std::vector<Account> decodeList(const std::string &encoded);
+      static std::string encodeList(const std::vector<Account> &entries);
       static std::string jsonEscape(const std::string &s);
    };