Add M365 Login plugin: Microsoft Entra ID sign-in for existing users

Adds a WordPress plugin that places a customisable "Sign in with
Microsoft" button on wp-login.php and signs existing users in via the
OpenID Connect authorization code flow with PKCE. Users are matched by
e-mail address only; no accounts are created.

Security: single-use state/nonce bound to an HttpOnly cookie, ID token
signature verification against Microsoft's JWKS (RS256 only) with
issuer/audience/tenant/expiry/nonce checks, optional tenant pinning,
account binding to the Microsoft object ID, e-mail domain allow-list,
client secret encrypted at rest (AES-256-GCM).

Admin: settings screen with connection, button and security tabs, live
button preview, colour presets, media-library icon picker, redirect URI
copy button and tenant connectivity test.

Packaging for WordPress.org: readme.txt with External services section,
GPL-2.0 license, uninstall.php, POT + German translations, .distignore,
build script, PHPCS config and CI running Plugin Check.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JJxAHYdMfKPoN4koRc4Ci2

bin/compile-mo.py

@@ -0,0 +1,103 @@
+#!/usr/bin/env python3
+"""Compiles every languages/*.po into a binary .mo (no gettext tools required).
+
+Usage: python3 bin/compile-mo.py
+"""
+import ast
+import glob
+import os
+import struct
+
+ROOT = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+
+
+def parse_po(path):
+    messages = {}
+    ctx = msgid = msgstr = None
+    plural = None
+    plurals = {}
+    section = None
+
+    def flush():
+        if msgid is None:
+            return
+        key = msgid if ctx is None else ctx + "\x04" + msgid
+        if plural is not None:
+            key = key + "\x00" + plural
+            value = "\x00".join(plurals[i] for i in sorted(plurals))
+        else:
+            value = msgstr or ""
+        if msgid == "" or value:
+            messages[key] = value
+
+    for raw in open(path, encoding="utf-8"):
+        line = raw.strip()
+        if not line or line.startswith("#"):
+            continue
+        if line.startswith("msgctxt "):
+            flush()
+            ctx, msgid, msgstr, plural, plurals = ast.literal_eval(line[8:]), None, None, None, {}
+            section = "ctx"
+        elif line.startswith("msgid_plural "):
+            plural = ast.literal_eval(line[13:])
+            section = "plural"
+        elif line.startswith("msgid "):
+            if section != "ctx":
+                flush()
+                ctx, msgstr, plural, plurals = None, None, None, {}
+            msgid = ast.literal_eval(line[6:])
+            section = "id"
+        elif line.startswith("msgstr["):
+            idx = int(line[7:line.index("]")])
+            plurals[idx] = ast.literal_eval(line[line.index("]") + 1:].strip())
+            section = ("pl", idx)
+        elif line.startswith("msgstr "):
+            msgstr = ast.literal_eval(line[7:])
+            section = "str"
+        elif line.startswith('"'):
+            chunk = ast.literal_eval(line)
+            if section == "ctx":
+                ctx += chunk
+            elif section == "id":
+                msgid += chunk
+            elif section == "plural":
+                plural += chunk
+            elif section == "str":
+                msgstr += chunk
+            elif isinstance(section, tuple):
+                plurals[section[1]] += chunk
+    flush()
+    return messages
+
+
+def write_mo(messages, path):
+    keys = sorted(messages)
+    ids = b""
+    strs = b""
+    offsets = []
+    for k in keys:
+        kb = k.encode("utf-8")
+        vb = messages[k].encode("utf-8")
+        offsets.append((len(ids), len(kb), len(strs), len(vb)))
+        ids += kb + b"\x00"
+        strs += vb + b"\x00"
+    n = len(keys)
+    keystart = 7 * 4 + 16 * n
+    valuestart = keystart + len(ids)
+    koffsets = []
+    voffsets = []
+    for o1, l1, o2, l2 in offsets:
+        koffsets += [l1, o1 + keystart]
+        voffsets += [l2, o2 + valuestart]
+    output = struct.pack("Iiiiiii", 0x950412DE, 0, n, 7 * 4, 7 * 4 + n * 8, 0, 0)
+    output += struct.pack("%di" % len(koffsets), *koffsets)
+    output += struct.pack("%di" % len(voffsets), *voffsets)
+    output += ids + strs
+    open(path, "wb").write(output)
+
+
+for po in sorted(glob.glob(os.path.join(ROOT, "languages", "*.po"))):
+    mo = po[:-3] + ".mo"
+    messages = parse_po(po)
+    write_mo(messages, mo)
+    print("Compiled %s (%d entries)" % (os.path.relpath(mo, ROOT), len(messages) - 1))