daemon: info and trusted replies fit one IPC message

[TeoSlayer]

Summary

One IPC message holds at most 1 MB (ipcutil.MaxMessageSize). The info reply lists every peer (~99 bytes each) and the trusted-peers reply every trust record (~129 bytes each), so past about 10,000 peers or 8,000 trust records the reply no longer fits. ipcutil.Write refuses it, writeLoop closes the client's connection, and the command fails with daemon disconnected, along with every later request on that connection.

Seen on the service-agent fleet (read-only check, 2026-10-06):

Agent	Peers	info reply
coinbase-spot-price	8,056	808,612 bytes (77% of the limit)
github-public	10,909	none: daemon closes the connection

What broke on such a node: pilotctl info, peers, connections, trust (agents hold over 20,000 trust records, so trust failed on all of them), and pilotctl send-message. Its first-contact info fails quietly, but the daemon has closed the connection, so the trust check and dial that follow fail too. The Python responder's post-handshake pilotctl peers check could never succeed there.

Change

• When a reply would exceed the budget, the daemon sends as many list rows as fit, adds peer_list_truncated / trusted_truncated: true, and leaves every other field intact (peers, connections and the other counts still give the totals). Replies that fit are byte-for-byte unchanged.
• What is kept: for info, all connection rows, then peers with an open connection first, then the rest in node order. For trust records, the newest first, which is the order pilotctl trust shows them in.
• pilotctl peers and pilotctl trust say when the daemon's list was cut (text and --json: truncated, plus daemon_peers for peers).

A complete listing on such nodes needs paging or a filtered query, which needs a driver change in common. This PR makes the commands work again without changing the protocol.

Tests

• TestInfoReplyFitsOneIPCMessage (12,000 peers, one in use): 10,139 rows in 1,048,512 bytes, flagged, in-use peer first. On main it fails with ipcutil.Read: EOF, the same "daemon disconnected".
• TestTrustedReplyFitsOneIPCMessage (24,000 records): the 8,127 newest, flagged. Fails on main the same way.
• TestMarshalRowsWithinBudgetKeepsAllThatFit: output ≤ budget, and one more row would not fit.
• TestCmdPeersReportsCutList, TestCmdTrustReportsCutList.
• go test ./pkg/... ./cmd/... ./internal/... -short passes.

Conflicts with #510 (both edit handleInfo); whichever merges second needs a small rebase.

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