docs: Rename DESIGN.md to TERMINAL-DESIGN.md

The doc was always about terminal panel rendering specifically;
'DESIGN.md' was too generic. Renaming makes the topic obvious from
the filename and avoids collision with future design docs in other
domains (architecture, API, brand, etc.).

git mv preserves the rename in history. Updated all 6 cross-refs:
README.md (Recent Updates v2.4.11 entry), rules/skill-agent-updates.md
(Terminal output section), skills/_lib/term.sh header, fleet-ops
fleet.sh header, summon SKILL.md, and summon.py (3 in-code mentions
plus 1 docstring).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

rules/skill-agent-updates.md

@@ -11,4 +11,4 @@ These APIs change frequently. For detailed reference (frontmatter fields, decisi
 
 ## Terminal output
 
-Skills that print to a TTY follow `docs/DESIGN.md` and source `skills/_lib/term.sh` for glyphs, colors, and layout helpers. Don't roll your own ANSI codes or state icons — `term_init` plus `term_state_icon` / `term_header` / `term_table_row` cover the common cases and keep the toolkit visually coherent.
+Skills that print to a TTY follow `docs/TERMINAL-DESIGN.md` and source `skills/_lib/term.sh` for glyphs, colors, and layout helpers. Don't roll your own ANSI codes or state icons — `term_init` plus `term_state_icon` / `term_header` / `term_table_row` cover the common cases and keep the toolkit visually coherent.

skills/_lib/term.sh

@@ -7,7 +7,7 @@
 #   term_init
 #
 # Honors: NO_COLOR, FORCE_COLOR, TERM_ASCII=1, FLEET_ASCII=1 (legacy).
-# Status: experimental — see docs/DESIGN.md.
+# Status: experimental — see docs/TERMINAL-DESIGN.md.
 
 # Guard against double-sourcing.
 [[ -n "${__TERM_SH_LOADED:-}" ]] && return 0

skills/fleet-ops/scripts/fleet.sh

@@ -19,7 +19,7 @@ LOG="$FLEET_DIR/activity.log"
 CONFIG="$FLEET_DIR/config"
 PID_FILE="$FLEET_DIR/daemon.pid"
 
-# Shared terminal-output helpers (see docs/DESIGN.md).
+# Shared terminal-output helpers (see docs/TERMINAL-DESIGN.md).
 # shellcheck source=../../_lib/term.sh
 . "$SCRIPT_DIR/../../_lib/term.sh"
 # Honor legacy FLEET_ASCII alongside TERM_ASCII.

skills/summon/SKILL.md

@@ -78,7 +78,7 @@ Mechanically identical — the file moves are the same regardless of which frami
 
 ## Display
 
-Output follows the [Terminal Panel Design System](../../docs/DESIGN.md) (panel header, body with `│` rail, footer, ASCII fallback when stdout isn't UTF-8). The candidate hierarchy is **Account → Project → Session**, with sessions globally numbered for picker selection (`3, 5, 7`).
+Output follows the [Terminal Panel Design System](../../docs/TERMINAL-DESIGN.md) (panel header, body with `│` rail, footer, ASCII fallback when stdout isn't UTF-8). The candidate hierarchy is **Account → Project → Session**, with sessions globally numbered for picker selection (`3, 5, 7`).
 
 ```
 ╭── 🪄 summon ──────────────────────────────────────────────── → mknv74 ───●

skills/summon/scripts/summon.py

@@ -13,7 +13,7 @@ Defaults:
 Auto-detects destination as the most-recently-active account.
 Source defaults to "all other accounts" — narrow with --from.
 
-Output rendering follows docs/DESIGN.md (Terminal Panel Design System).
+Output rendering follows docs/TERMINAL-DESIGN.md (Terminal Panel Design System).
 """
 
 from __future__ import annotations
@@ -33,7 +33,7 @@ from typing import Iterable
 
 
 # ============================================================
-#  DESIGN: terminal panel rendering (per docs/DESIGN.md)
+#  DESIGN: terminal panel rendering (per docs/TERMINAL-DESIGN.md)
 # ============================================================
 
 def _stdout_supports_unicode() -> bool:
@@ -95,7 +95,7 @@ def trunc(s: str, width: int) -> str:
     return s[: width - vlen(ell)] + ell
 
 
-# Brand emoji for summon (not in DESIGN.md registry yet — registering here)
+# Brand emoji for summon (not in TERMINAL-DESIGN.md registry yet — registering here)
 BRAND_EMOJI = "🪄"
 BRAND_ASCII = "[S]"
 
@@ -1017,7 +1017,7 @@ def main():
         echo(panel_close())
         return
 
-    # Summary line at the TOP per DESIGN.md.
+    # Summary line at the TOP per TERMINAL-DESIGN.md.
     sep = Term.g("·", "|")
     if len(source_accounts) == 1:
         src_email = source_accounts[0].email or source_accounts[0].short