The tip-manual gate passes when tips appear outside the tips table #1480

Seen on dev@debffabf6. Surfaced while verifying #1389; introduced by it.

What happened

TestEveryTipIsOnTheManualPage checks manual.Chat().Mentions(n.text) for each tip. That searches the whole chat corpus, so a tip can be deleted from the hints-and-tips.md table, moved out of order, or appear only in another page while the gate stays green. The change entry and manual describe a stronger, word-for-word table contract.

Replication

Deterministic (no model). In a disposable checkout, move one tip line out of the table section into another chat page, then run go test ./internal/tui3 -run TestEveryTipIsOnTheManualPage -count=1. The test still passes because the words remain somewhere in the corpus. Restore the checkout afterward. Reorder two table lines for a second passing counterexample.

Where

internal/tui3/hometip_test.go:237 at dev@debffabf6 uses corpus-wide Mentions. The table is in internal/manual/chat/hints-and-tips.md under ## Every hint codeaf can show.

The fix

Read that exact table section, parse its ordered tip lines, and compare them with the code's ordered tip list.

Acceptance

• e2e: a documentation command or targeted test fails if a visible tip is absent from the table or its order changes without a matching code change.
• Unit: the gate rejects the two counterexamples above and accepts the current table.
• Correct the change entry's gate claim in invalidates.