discord-bot: fix "no response", serialize turns, attribution, mentions, post-at-bottom

client.py: send() falls back to ResultMessage.result when no TextBlock streams
(the "(no response)" bug) and reconnects+retries once on a closed SDK session.

message_handler.py: per-thread turn lock so messages arriving mid-turn or from a
second user queue in order (nothing dropped); per-session requester-attribution
env (discord_id -> users.json key), pinned to the thread opener; _USER_MAP caches
only on a successful load; final answer posts as a fresh message at the BOTTOM
(no edit-in-place); a <@id> tag goes out as a fresh send so it actually pings.

main.py: allowed_mentions permits user pings, blocks @everyone/@here/roles.

DISCORD_CLAUDE.md: no thread auto-delete; tiered close-out (Q&A -> one-line rolling
log, substantive -> /save); @mention guidance; opener-pinned attribution note.

whoami-block.sh / sync.sh: bot-context attribution (Executed by ClaudeTools Bot /
Requested by <person>; git author = mapped requester, committer = bot). Strict
no-op for interactive sessions.

users.json: discord_id for Mike/Howard; added Winter Williams (bot-only, full trust).

Reviewed by Code Review Agent + Grok + Gemini (Gemini's "malformed email" finding
verified as a false positive).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.claude/users.json

@@ -13,6 +13,7 @@
       ],
       "git_name": "Mike Swanson",
       "git_email": "mike@azcomputerguru.com",
+      "discord_id": "264814939619721216",
       "notes": "Owner. Full access to everything. Primary machine: GURU-5070 (as of 2026-05-25). Previous machine DESKTOP-0O8A1RL retired."
     },
     "howard": {
@@ -26,6 +27,7 @@
       ],
       "git_name": "Howard Enos",
       "git_email": "howard@azcomputerguru.com",
+      "discord_id": "624667664501178379",
       "gitea_username": "howard",
       "notes": "Employee, Mike's brother. Full trust. Same access as Mike for MSP tracking and daily work. Has own Gitea account (howard) with admin access to all repos. Password rotated 2026-04-21 — stored in Howard's 1Password, not in this file."
     },
@@ -38,6 +40,18 @@
       "discord_id": "261978810713505792",
       "known_machines": [],
       "notes": "Web developer contractor. No direct ClaudeTools CLI access. Interacts only through the Discord bot. Authorized scope: M365/365 remediations (remediation-tool skill), IX hosting changes (DNS, cPanel accounts, file management on IX/Websvr), Syncro read. Cannot modify bot behavior, skills, CLAUDE.md, DISCORD_CLAUDE.md, users.json, vault entries, or git history."
+    },
+    "winter": {
+      "full_name": "Winter Williams",
+      "email": "wwilliams@azcomputerguru.com",
+      "role": "tech",
+      "title": "Syncro SME (Discord bot only)",
+      "syncro_user_id": 1737,
+      "discord_id": "624666486362996755",
+      "git_name": "Winter Williams",
+      "git_email": "wwilliams@azcomputerguru.com",
+      "known_machines": [],
+      "notes": "Full trust. Go-to SME for Syncro / ticketing — defer Syncro decisions to her. Interacts ONLY through the Discord bot; no installed Claude CLI sessions."
     }
   },
   "roles": {