fix: delete AskUserQuestion fallback (root cause of forever war)

The /plan-eng-review skill failed to fire AskUserQuestion on a real
plan review and surfaced 4 calibration decisions via prose instead.
Investigation traced this to a "fallback when neither variant is
callable" clause in the preamble that the model rationalizes around
as a general escape hatch from "fanning out round-trip AUQs," even
when an AUQ variant IS callable. Codex review confirmed the fallback
exists in 8 inline sites with 2 surviving escape hatches the original
narrowing missed (a "genuinely trivial" exception duplicated across
all 4 plan-* templates, and a "outside plan mode, output as prose
and stop" branch in the preamble itself).

Net deletion in skill text. Closes both branches of the deleted
fallback (plan-file write AND prose-and-stop) and the trivial-fix
exception with a single hard rule:

  If no AskUserQuestion variant appears in your tool list, this
  skill is BLOCKED. Stop, report `BLOCKED — AskUserQuestion
  unavailable`, and wait for the user.

Honest about being a model directive, not a runtime guard — none of
the PTY harness helpers enforce BLOCKED today. The architectural
improvement is that the model has fewer alternatives to obey it
against. Runtime enforcement is a follow-up TODO.

Sources changed:
- scripts/resolvers/preamble/generate-ask-user-format.ts: delete both
  fallback branches; replace with 1-line BLOCKED rule
- scripts/resolvers/preamble/generate-completion-status.ts: delete
  fallback in generatePlanModeInfo
- plan-eng-review/SKILL.md.tmpl: delete fallback at Step 0 + Sections
  1-4 (5 instances) + delete trivial-fix exception
- office-hours/SKILL.md.tmpl: delete fallback in approach-selection
- plan-ceo-review/SKILL.md.tmpl: delete trivial-fix exception
- plan-design-review/SKILL.md.tmpl: delete trivial-fix exception
- plan-devex-review/SKILL.md.tmpl: delete trivial-fix exception

Generated SKILL.md regen lands in a follow-up commit per the bisect
convention (template changes separate from regenerated output).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

plan-design-review/SKILL.md.tmpl

@@ -348,7 +348,7 @@ Follow the AskUserQuestion format from the Preamble above. Additional rules for
 * Present 2-3 options. For each: effort to specify now, risk if deferred.
 * **Map to Design Principles above.** One sentence connecting your recommendation to a specific principle.
 * Label with issue NUMBER + option LETTER (e.g., "3A", "3B").
-* **Escape hatch (tightened):** If a section has zero findings, state "No issues, moving on" and proceed. If it has findings, use AskUserQuestion for each — a gap with an "obvious fix" is still a gap and still needs user approval before any change lands in the plan. Only skip AskUserQuestion when the fix is genuinely trivial AND there are no meaningful design alternatives. When in doubt, ask.
+* **Zero findings:** if a section has zero findings, state "No issues, moving on" and proceed. Otherwise, use AskUserQuestion for each gap — a gap with an "obvious fix" is still a gap and still needs user approval before any change lands in the plan.
 * **NEVER use AskUserQuestion to ask which variant the user prefers.** Always create a comparison board first (`$D compare --serve`) and open it in the browser. The board has rating controls, comments, remix/regenerate buttons, and structured feedback output. Use AskUserQuestion ONLY to notify the user the board is open and wait for them to finish — not to present variants inline and ask "which do you prefer?" That is a degraded experience.
 
 ## Required Outputs