Add real IMAP4rev1/POP3 implementations, DKIM/DMARC/SPF, SpamAssassin delivery hook

IMAP (RFC 3501): LOGIN through UID, previously all stubs except
CAPABILITY/LOGOUT/a partial APPEND. Multi-folder support with per-folder
UID/flag indexing (new MailFolder class, backed by .uidvalidity/.uidnext/
.imapindex sidecar files), ENVELOPE support (new MessageHeaders class:
header parsing, address-list parsing, IMAP quoting), and shared
cursor-based argument parsing (new IMAPArgs class: sequence sets, flag
lists, dates, folder-name normalization, and path-traversal protection
via isValidFolderName - a bare ".." folder name would otherwise resolve
into a sibling user's mailbox directory).

POP3 (RFC 1939): USER through QUIT, previously only CAPA. Added UIDL.
POP3 handlers use cursor-based parsing throughout rather than indexed
access - ZString's copy constructor doesn't copy its `list` field, and
POP3's dispatch passes the request by value, so indexed access into a
copy was silently reading nothing.

SMTP: DMARC evaluation added to the DATA-terminator path (DKIM
verification + alignment/policy, Authentication-Results header,
conditional rejection matching RFC 7489 6.3's p=reject + sampled pct=).
AUTH LOGIN now handles RFC 4954's optional inline initial response
(e.g. Python smtplib's "AUTH LOGIN <base64>" in one line) instead of
only the exact three-line form. Outbound relay now forces IPv4
(AF_INET) instead of AF_UNSPEC - this server's IPv4 has a correct PTR
record and SPF coverage, its IPv6 doesn't, and Gmail was rejecting
outbound mail with 550 5.7.25 as a result.

Delivery pipeline: local delivery now runs the message through
SpamAssassin (new SpamAssassinFilter class, speaking spamd's PROCESS
protocol directly over a raw socket - fails open/delivers unscanned if
spamd is unreachable) instead of a plain hardlink, since scanning can
tag/modify content.

BARANTMailConfig: extracted config loading into its own class.

compile: (see individual file changes - build script adjustments to
match the above).

Deliberately excluded from this commit: barantmail.log/
barantmail-service.log (operational logs, not source - barantmail.log
in particular was the runaway 55GB/12.9GB file from a busy-loop bug
fixed separately in ServerCore) and barantmail.cfg (this server's own
live deployment config, matching how APIServer's equivalent
config also stays untracked).

IMAPServer.h

@@ -2,10 +2,13 @@
 # define __IMAPServer_h__
 
 # include "TCPServer.h"
+# include "TLSInfo.h"
 # include "Exception.h"
+# include "IMAPSession.h"
 # include "MailFileSystem.h"
 # include "__IMAP_APPEND.h"
 # include "__IMAP_AUTHENTICATE.h"
+# include "__IMAP_CAPABILITY.h"
 # include "__IMAP_CHECK.h"
 # include "__IMAP_CLOSE.h"
 # include "__IMAP_COPY.h"
@@ -16,7 +19,9 @@
 # include "__IMAP_FETCH.h"
 # include "__IMAP_LIST.h"
 # include "__IMAP_LOGIN.h"
+# include "__IMAP_LOGOUT.h"
 # include "__IMAP_LSUB.h"
+# include "__IMAP_NOOP.h"
 # include "__IMAP_RENAME.h"
 # include "__IMAP_SEARCH.h"
 # include "__IMAP_SELECT.h"
@@ -32,21 +37,31 @@ namespace mail {
    class IMAPServer : public core::TCPServer {
 
     public:
-      IMAPServer(core::EPoll &epoll, std::string hostName, MailFileSystem &mailFileSystem, core::IPAddress ipAddress)
-	: TCPServer(epoll, ipAddress, " ", 10, "IMAP Server"), mailFileSystem(mailFileSystem), hostName(hostName) {	   
+      IMAPServer(core::EPoll &epoll, std::string hostName, MailFileSystem &mailFileSystem,
+                 core::IPAddress ipAddress, core::TLSInfo *tlsInfo)
+	: TCPServer(epoll, ipAddress, tlsInfo, " ", 10, "IMAP Server"), mailFileSystem(mailFileSystem), hostName(hostName) {
          commands.add(_imap_append, "APPEND");
-         commands.add(_imap_authenticate, "AUTHENTCATE");
+         // Was registered as "AUTHENTCATE" (missing the I) - no
+         // correctly-spelled client request could ever match it.
+         commands.add(_imap_authenticate, "AUTHENTICATE");
+         // RFC 3501 6.1.1/6.1.2/6.1.3: CAPABILITY, NOOP, and LOGOUT MUST
+         // be supported in every connection state - none of the three
+         // were registered at all before.
+         commands.add(_imap_capability, "CAPABILITY");
          commands.add(_imap_check, "CHECK");
          commands.add(_imap_close, "CLOSE");
          commands.add(_imap_copy, "COPY");
          commands.add(_imap_create, "CREATE");
          commands.add(_imap_delete, "DELETE");
-         commands.add(_imap_examine, "EXAAMINE");
+         // Was registered as "EXAAMINE" (double A) - same problem.
+         commands.add(_imap_examine, "EXAMINE");
          commands.add(_imap_expunge, "EXPUNGE");
          commands.add(_imap_fetch, "FETCH");
          commands.add(_imap_list, "LIST");
          commands.add(_imap_login, "LOGIN");
+         commands.add(_imap_logout, "LOGOUT");
          commands.add(_imap_lsub, "LSUB");
+         commands.add(_imap_noop, "NOOP");
          commands.add(_imap_rename, "RENAME");
          commands.add(_imap_search, "SEARCH");
          commands.add(_imap_select, "SELECT");
@@ -60,10 +75,23 @@ namespace mail {
 
       MailFileSystem &mailFileSystem;
       std::string hostName;
-      
+
+      // Without this override, TCPServer's default getSocketAccept()
+      // returns a plain TCPSession for every accepted connection, not
+      // an IMAPSession - IMAPSession::onConnected() (the greeting
+      // banner) then never fires, and IMAPCommand's session casts
+      // ((IMAPSession &)session) reinterpret a TCPSession's memory as
+      // an IMAPSession, undefined behavior the moment any handler
+      // touches a member IMAPSession actually has and TCPSession
+      // doesn't.
+      IMAPSession *getSocketAccept(core::EPoll &ePoll) override {
+         return new IMAPSession(ePoll, *this);
+      }
+
     private:
       __IMAP_APPEND _imap_append;
       __IMAP_AUTHENTICATE _imap_authenticate;
+      __IMAP_CAPABILITY _imap_capability;
       __IMAP_CHECK _imap_check;
       __IMAP_CLOSE _imap_close;
       __IMAP_COPY _imap_copy;
@@ -74,7 +102,9 @@ namespace mail {
       __IMAP_FETCH _imap_fetch;
       __IMAP_LIST _imap_list;
       __IMAP_LOGIN _imap_login;
+      __IMAP_LOGOUT _imap_logout;
       __IMAP_LSUB _imap_lsub;
+      __IMAP_NOOP _imap_noop;
       __IMAP_RENAME _imap_rename;
       __IMAP_SEARCH _imap_search;
       __IMAP_SELECT _imap_select;