fix(#2402): honor response_language across orchestrator output + UAT checkpoint renderer (#2457)

* fix(#2402): honor response_language across orchestrator output + UAT checkpoint renderer

Replays the in-flight bot branch fix/2402-response-language-orchestrator-coverage
(seven commits, never pushed) onto current origin/next as a single squashed commit.
The original work was substantial and correct; this commit preserves its full scope,
trimmed where rebase conflicts + workflow size budgets required it.

Three independent layers where response_language was being dropped are closed:

Layer 1 — orchestrator-facing directives across workflows. Adds the strong
"All user-facing output in this workflow MUST be presented in {response_language};
technical terms, code, paths, and subagent prompts stay in English" directive
to ~40 workflows that previously either lacked it entirely (verify-work,
new-project, new-milestone, quick, manager, and ~35 more) or carried only
the weak subagent-prompt-only form (plan-phase, execute-phase). The directive
covers narration between tool calls and banner output, not just the
AskUserQuestion prompts.

Layer 2 — UAT checkpoint renderer (src/uat.cts). buildCheckpoint now accepts
an optional responseLanguage parameter and renders the frame strings
("CHECKPOINT: Verification Required", "Type `pass` or describe what's wrong.")
in any of 9 languages (English/Spanish/French/German/Portuguese/Japanese/
Chinese/Korean/Italian) with an alias table covering ~30 input variants
(en, es, español, ja, 日本語, etc.). cmdRenderCheckpoint reads
config.response_language via loadConfig(cwd) and passes it through, so the
byte-for-byte block verify-work.md reprints verbatim is already localized
when written — preserving the anti-injection hygiene rule at verify-work.md
(the model is forbidden to translate after the fact). CJK display width is
computed by East Asian Width property ranges (W/F) so the right ║ border of
the banner stays aligned for full-width characters. English fallback is
byte-identical to the pre-fix behavior when response_language is unset or
unrecognized.

Layer 3 — literal English report templates in execute-phase. The top-of-
workflow directive covers all template sites (templates are a structural
source, not literal output). Inline render-language notes that previously
sat at each template site were removed during the squash because they
pushed execute-phase.md over its frozen pre-phase-6 byte ceiling
(93600 — ADR-857 Phase 6 capstone). The single top directive covers the
same surface with fewer bytes.

Also extends src/docs.cts and src/init.cts to propagate response_language
into the init JSON bundle of the additional workflows so the directive can
read it.

Tests added:
- tests/uat.test.cjs: buildCheckpoint with unset/unrecognized language falls
  back to English default; recognized language swaps only the two frame
  strings while structural lines stay untouched; CJK display-width regression
  (independent recomputation of East Asian Width W/F ranges).
- tests/workspace.test.cjs, tests/docs-update.test.cjs: response_language
  wiring through docs.cts/init.cts.

References: #2402; reporter's three-layer triage + Layer-4 follow-up; the
byte-for-byte anti-injection hygiene rule at verify-work.md (the reason
Layer 2 must be renderer-side, not model-translated).

This is a squash of the in-flight bot branch — seven commits representing
the original implementation plus its subsequent fix/CJK-padding/test/
changeset/regen cycles, none of which were ever pushed or PR'd. The squash
captures the final coherent state.

* chore(#2402): backfill pr:2457 in .changeset/2402-response-language-orchestrator-coverage.md

* chore(#2402): regen golden + size baseline after rebase against #2315 (PR #2451)

Rebase conflicts were entirely in generated artifacts (golden-install-parity
fixtures + workflow-size-baseline.json). After taking theirs during rebase,
regenerated cleanly against the merged source tree.

gsd-core/workflows/plan-phase.md

@@ -83,7 +83,7 @@ When `CONTEXT_WINDOW >= 500000`, the planner prompt includes the 3 most recent p
 
 Parse JSON for: `researcher_model`, `planner_model`, `checker_model`, `research_enabled`, `plan_checker_enabled`, `nyquist_validation_enabled`, `commit_docs`, `text_mode`, `phase_found`, `phase_dir`, `phase_number`, `phase_name`, `phase_slug`, `padded_phase`, `has_research`, `has_context`, `has_reviews`, `has_plans`, `plan_count`, `phase_status` (#3569), `planning_exists`, `roadmap_exists`, `phase_req_ids`, `response_language`, `granularity`.
 
-**If `response_language` is set:** Include `response_language: {value}` in all spawned subagent prompts so any user-facing output stays in the configured language.
+**If `response_language` is set:** All user-facing orchestrator output MUST be in `{response_language}`; technical terms, code, paths, and subagent prompts stay in English. Pass `response_language: {value}` into every spawned subagent prompt.
 
 **File paths (for <files_to_read> blocks):** `state_path`, `roadmap_path`, `requirements_path`, `context_path`, `research_path`, `verification_path`, `uat_path`, `reviews_path`. These are null if files don't exist.