fix(#2636): surface gsd-sdk query failures and add workflow↔handler parity check (#2656)

* fix(#2636): surface gsd-sdk query failures and add workflow↔handler parity check

Root cause: workflows invoked `gsd-sdk query agent-skills <slug>` with a
trailing `2>/dev/null`, swallowing stderr and exit code. When the installed
`@gsd-build/sdk` npm was stale (pre-query), the call resolved to an empty
string and `agent_skills.<slug>` config was never injected into spawn
prompts — silently. The handler exists on main (sdk/src/query/skills.ts),
so this is a publish-drift + silent-fallback bug, not a missing handler.

Fix:
- Remove bare `2>/dev/null` from every `gsd-sdk query agent-skills …`
  invocation in workflows so SDK failures surface to stderr.
- Apply the same rule to other no-fallback calls (audit-open, write-profile,
  generate-* profile handlers, frontmatter.get in commands). Best-effort
  cleanup calls (config-set workflow._auto_chain_active false) keep
  exit-code forgiveness via `|| true` but no longer suppress stderr.

Parity tests:
- New: tests/bug-2636-gsd-sdk-query-silent-swallow.test.cjs — fails if any
  `gsd-sdk query agent-skills … 2>/dev/null` is reintroduced.
- Existing: tests/gsd-sdk-query-registry-integration.test.cjs already
  asserts every workflow noun resolves to a registered handler; confirmed
  passing post-change.

Note: npm republish of @gsd-build/sdk is a separate release concern and is
not included in this PR.

* fix(#2636): address review — restore broken markdown fences and shell syntax

The previous commit's mass removal of '2>/dev/null' suffixes also
collapsed adjacent closing code fences and 'fi' tokens onto the
command line, producing malformed markdown blocks and 'truefi' /
'true   fi' shell syntax errors in the workflows.

Repaired sites:
- commands/gsd/quick.md, thread.md (frontmatter.get fences)
- workflows/complete-milestone.md (audit-open fence)
- workflows/profile-user.md (write-profile + generate-* fences)
- workflows/verify-work.md (audit-open --json fence)
- workflows/execute-phase.md (truefi -> true / fi)
- workflows/plan-phase.md, discuss-phase-assumptions.md,
  discuss-phase/modes/chain.md (true   fi -> true / fi)

All 5450 tests pass.

get-shit-done/workflows/execute-phase.md

@@ -69,7 +69,7 @@ Load all context in one call:
 ```bash
 INIT=$(gsd-sdk query init.execute-phase "${PHASE_ARG}")
 if [[ "$INIT" == @file:* ]]; then INIT=$(cat "${INIT#@file:}"); fi
-AGENT_SKILLS=$(gsd-sdk query agent-skills gsd-executor 2>/dev/null)
+AGENT_SKILLS=$(gsd-sdk query agent-skills gsd-executor)
 ```
 
 Parse JSON for: `executor_model`, `verifier_model`, `commit_docs`, `parallelization`, `branching_strategy`, `branch_name`, `phase_found`, `phase_dir`, `phase_number`, `phase_name`, `phase_slug`, `plans`, `incomplete_plans`, `plan_count`, `incomplete_count`, `state_exists`, `roadmap_exists`, `phase_req_ids`, `response_language`.
@@ -130,7 +130,7 @@ inline path for each plan.
 ```bash
 # REQUIRED: prevents stale auto-chain from previous --auto runs
 if [[ ! "$ARGUMENTS" =~ --auto ]]; then
-  gsd-sdk query config-set workflow._auto_chain_active false 2>/dev/null
+  gsd-sdk query config-set workflow._auto_chain_active false || true
 fi
 ```
 </step>
@@ -1339,7 +1339,7 @@ spawn template, and the two `workflow.drift_*` config keys.
 Verify phase achieved its GOAL, not just completed tasks.
 
 ```bash
-VERIFIER_SKILLS=$(gsd-sdk query agent-skills gsd-verifier 2>/dev/null)
+VERIFIER_SKILLS=$(gsd-sdk query agent-skills gsd-verifier)
 ```
 
 ```