/ctx shows the default base prompt as split rows

The /ctx report lumped the whole default base prompt into one row, so the Prompt snippets and Prompt guidelines that tools register were invisible as such: their cost was in the token count, but a reader could not tell which guideline or snippet it was, or who registered it.

The default base prompt now renders as separate rows: one base prompt row holding the boilerplate (the identity line, the custom-tools line, and the pi documentation block), one available tools row carrying all Prompt snippets, and one row per Prompt guideline, each attributed to its source (builtin for pi's default bullets, extension for the rest). Token totals do not change: the total still estimates the prompt as the one unit the provider sees, and the report total of a session is unchanged. A custom prompt stays a single row.

The governing invariant: the section texts concatenate to the exact base prompt. Prompt-injection detection compares the sent system prompt with that concatenation, so an unmodified session must still report no injection and an extension-modified prompt must still be detected. The boilerplate therefore lives in the gaps the split rows fill: it is three section pieces under one key, and the report merges them into the single base prompt row.

Considered options

• One row, unchanged. Simplest, but the snippet and guideline cost stays invisible.
• Split rows without the exact-concatenation invariant. Simpler row construction, but injection detection would need a second, parallel reconstruction and the two could drift.
• Split rows with the invariant (chosen). The boilerplate is stored around the split pieces; the merge is a single-key join at report time.

Consequences

• The row kind set gains tools and guideline; both carry a dash in the usage columns, like the other section rows.
• The report row for the boilerplate holds the boilerplate text with the snippet and guideline bullets removed; expanding it shows that text, not the full prompt.
• A registered guideline identical to a pi default bullet keeps the builtin source (it is the default bullet, and dedup keeps the first occurrence in prompt order).