docs(arch): Add ARCHITECTURE and CLAUDE, init repo

Bring the Diag-OS variant of the Blanton A/B/C Tera Term scripts under
version control, alongside the SONiC-based Blanton_TTL_Script.

- ARCHITECTURE.md: Diag OS flow, acc_* command taxonomy, swutil addressing,
  TH6 test sequence side effects, and a 6-phase roadmap
- CLAUDE.md: stack, per-script command inventory, conventions, footguns
- .gitattributes: keep .ttl as CRLF (Windows-only), LF for everything else
- .gitignore: secret/, For_AI/, *.log, publish/ output
- secret/: README + config_secret.ttl.example for per-unit overrides
- Logs/ and utils/ placeholders (logopen needs Logs/ to pre-exist)

Known gaps documented, not fixed here: 2_Blanton_Script_B.ttl includes
utils/show_margin_status.ttl which does not exist yet, and its while loop
has no pause despite the "every 10mins" comment.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SoEiorvuhmdTkpZWtEhJwq

secret/config_secret.ttl.example

@@ -0,0 +1,32 @@
+; =============================================================================
+; config_secret.ttl.example — 現場 / per-unit 參數範本
+; -----------------------------------------------------------------------------
+; 用法：
+;   cp secret/config_secret.ttl.example secret/config_secret.ttl
+;   編輯 config_secret.ttl，把所有 __CHANGE_ME__ 換成實際值
+;
+; 這個檔 **不進 git**（.gitignore: secret/*）。
+; Tera Term 端把 src/Script_ABC_Blanton_Diag/ 複製到工作目錄時，
+; 一併把 config_secret.ttl 放到同一層（config.ttl 以相對路徑 include）。
+;
+; ⚠️ 目前 config.ttl 尚未 include 這個檔（Diag OS 無登入互動、沒有帳密要藏）。
+;    等到真的需要 per-unit 覆寫時，在 config.ttl 加：
+;        include "config_secret.ttl"
+; =============================================================================
+
+; ── DUT 連線 ────────────────────────────────────────────────
+; 這台 DUT 的 diag console 掛在哪個 COM port（僅供記錄，Tera Term 連線仍是手動選）
+dut_com_port   = "__CHANGE_ME__"          ; 例："COM39"
+
+; ── Prompt 覆寫 ─────────────────────────────────────────────
+; Diag image 換版或 hostname 被設定時，用這裡覆寫 config.ttl 的預設值。
+; 一定要跟畫面上看到的完全一致（含空白），否則所有 wait 都會卡住。
+prompt_diag    = "__CHANGE_ME__"          ; 預設："root@(none):~#"
+
+; ── 登入（若未來的 Diag image 加上帳密才需要）────────────────
+dut_username   = "__CHANGE_ME__"
+dut_password   = "__CHANGE_ME__"
+
+; ── per-unit 覆寫 ───────────────────────────────────────────
+; 每台機器不同、又不該進 repo 的東西放這裡（埠清單、BDF、序號…）
+dut_serial     = "__CHANGE_ME__"