pi bridge: RemoteMcpClient is now the only copy (pi-extensions retired mcp-loader.ts)

pi-extensions 750b2a8 removed mcp-loader.ts in favour of pi's built-in MCP
support (builtin:mcp, ~/.pi/agent/mcp.json). The bridge's RemoteMcpClient was
vendored from that file and kept in step by an MCP-STREAMABLE-HTTP-CLIENT-SYNC
token, checked by scripts/check-mcp-client-sync.sh. With the canonical copy
gone the guard could only ever SKIP (or, on images that still bake
/opt/pi-extensions/extensions/mcp-loader.ts, compare against a dead file), so
it is removed rather than left looking like a check.

Comment and README only; no code change. The bridge still type-strips and
imports (node 24), and evaluateDormancy is exported as before. The README
records why MemPalace itself does not move to the built-in: its wake-up,
mailbox, feed and stamping need their own client, and built-in tools would be
mcp__mempalace__* with codemode exposure by default.

scripts/check-mcp-client-sync.sh

@@ -1,77 +0,0 @@
-#!/usr/bin/env bash
-# check-mcp-client-sync.sh — drift guard for the vendored streamable-HTTP MCP client.
-#
-# The RemoteMcpClient in extensions/pi/mempalace.ts is a VENDORED copy of the
-# canonical implementation in pi-extensions/extensions/mcp-loader.ts (the two
-# repos ship independently, so a shared import isn't practical for one small,
-# protocol-frozen class — see the annotated header in mempalace.ts).
-#
-# Both blocks carry a matching sync token:
-#     MCP-STREAMABLE-HTTP-CLIENT-SYNC: vN
-# Bump it in BOTH files whenever the streamable-HTTP protocol handling changes.
-# This guard fails when the tokens diverge, so a protocol fix in one file can't
-# silently skip the other.
-#
-# It is a LOCAL developer guard: it needs the sibling pi-extensions checkout to
-# compare against. If that isn't found it SKIPS (exit 0) rather than failing —
-# so it's safe to wire into CI that only checks out this repo.
-#
-# Point it at a specific checkout with:  PI_EXTENSIONS_DIR=/path/to/pi-extensions
-set -euo pipefail
-
-REPO_ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
-VENDORED="$REPO_ROOT/extensions/pi/mempalace.ts"
-
-TOKEN_RE='MCP-STREAMABLE-HTTP-CLIENT-SYNC: v[0-9]+'
-extract_token() { grep -oE "$TOKEN_RE" "$1" 2>/dev/null | head -1 | grep -oE 'v[0-9]+' || true; }
-
-if [[ ! -f "$VENDORED" ]]; then
-  echo "ERROR: vendored file not found: $VENDORED" >&2
-  exit 1
-fi
-
-VENDORED_TOKEN="$(extract_token "$VENDORED")"
-if [[ -z "$VENDORED_TOKEN" ]]; then
-  echo "FAIL: no '$TOKEN_RE' token in $VENDORED" >&2
-  echo "      The vendored RemoteMcpClient must carry a sync token." >&2
-  exit 1
-fi
-
-# Locate the canonical mcp-loader.ts across common dev layouts.
-CANDIDATES=(
-  "${PI_EXTENSIONS_DIR:-}/extensions/mcp-loader.ts"
-  "$REPO_ROOT/../pi-extensions/extensions/mcp-loader.ts"
-  "/workspace/pi-extensions/extensions/mcp-loader.ts"
-  "$HOME/src/pi-extensions/extensions/mcp-loader.ts"
-  "$HOME/src/src_local/pi-extensions/extensions/mcp-loader.ts"
-  "/opt/pi-extensions/extensions/mcp-loader.ts"
-)
-CANONICAL=""
-for c in "${CANDIDATES[@]}"; do
-  [[ -n "$c" && -f "$c" ]] && { CANONICAL="$c"; break; }
-done
-
-if [[ -z "$CANONICAL" ]]; then
-  echo "SKIP: canonical pi-extensions/extensions/mcp-loader.ts not found — cannot compare."
-  echo "      (vendored token: $VENDORED_TOKEN). Set PI_EXTENSIONS_DIR to enable the check."
-  exit 0
-fi
-
-CANONICAL_TOKEN="$(extract_token "$CANONICAL")"
-if [[ -z "$CANONICAL_TOKEN" ]]; then
-  echo "FAIL: no '$TOKEN_RE' token in canonical $CANONICAL" >&2
-  exit 1
-fi
-
-if [[ "$VENDORED_TOKEN" != "$CANONICAL_TOKEN" ]]; then
-  echo "FAIL: MCP client sync token drift." >&2
-  echo "      vendored  ($VENDORED): $VENDORED_TOKEN" >&2
-  echo "      canonical ($CANONICAL): $CANONICAL_TOKEN" >&2
-  echo "      A streamable-HTTP protocol change landed in one file but not the other." >&2
-  echo "      Reconcile RemoteMcpClient in both, then bump the token in BOTH to match." >&2
-  exit 1
-fi
-
-echo "OK: MCP client sync token matches ($VENDORED_TOKEN)."
-echo "    vendored:  $VENDORED"
-echo "    canonical: $CANONICAL"