fix(#2072): thread resolved model into routed-agent spawns (assumptions-analyzer, code-reviewer, code-fixer)

model_overrides / models.<phaseType> were silently inert for gsd-assumptions-analyzer,
gsd-code-reviewer, and gsd-code-fixer on Claude Code: resolveModelInternal honors them,
but the workflows spawned these agents with no model= param, so the resolved value
never reached the Agent tool and the agents inherited the session model — no warning.

Fix — thread each agent's resolved model at every spawn site (the established
plan-phase pattern; the architecture-consistent Claude mechanism, since 13 other
agents already thread their model):
- discuss-phase-assumptions.md: `resolve-model gsd-assumptions-analyzer --raw`
  → ANALYZER_MODEL, threaded.
- code-review.md + code-review-fix.md (re-review): `resolve-model gsd-code-reviewer --raw`
  → REVIEWER_MODEL, threaded.
- code-review-fix.md (both fixer spawns): `resolve-model gsd-code-fixer --raw`
  → FIXER_MODEL, threaded (same silently-inert bug, same file — folded in per review).
- quick.md review step: was reusing `{executor_model}` for gsd-code-reviewer (so the
  reviewer's own override was ignored); init.quick now resolves `reviewer_model`
  (gsd-code-reviewer) and the spawn threads it.

resolve-model --raw returns the bare model string (resolve-execution --raw would
return effort — wrong). The resolver maps these agents to phaseType discuss /
verification / execution, so models.<phaseType> apply too.

Scope: the three agents reachable from the two issue-named workflows + quick.md. The
wider systemic class (other agents in UNTOUCHED workflows with the same pattern) stays
documented on the issue for a maintainer-scoped structural decision (thread-at-source
vs embed-at-install like #2256), not widened here.

Docs: the stale "discuss — reserved, no subagent today" model-profile tables now list
gsd-assumptions-analyzer and the verification row includes gsd-code-reviewer, across
the English docs, the shipped gsd-core/references/model-profiles.md reference, and the
ja-JP / zh-CN / ko-KR / pt-BR locale mirrors.

Tests:
- tests/model-resolver.test.cjs: #2072 acceptance — model_overrides and
  models.discuss/verification/execution resolve for all three agents.
- tests/model-routing-spawn-threading.test.cjs: every spawn of the three agents threads
  a resolved model (fails pre-fix); a header-precise parity guard fails the suite if a
  new un-threaded spawn of any of them regresses.
All 16 golden-install-parity fixtures + the workflow size baseline regenerated for the
changed shipped files (4 workflows + the reference doc); bin/lib is excluded from parity.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/fixtures/golden-install-parity/opencode.json

@@ -164,7 +164,7 @@
   "gsd-core/references/loop-hook-dispatch.md": "32e5dfb4dba76987",
   "gsd-core/references/mandatory-initial-read.md": "fe59abce693717cf",
   "gsd-core/references/model-profile-resolution.md": "858c16730df68ac2",
-  "gsd-core/references/model-profiles.md": "d6ed560db6357ad2",
+  "gsd-core/references/model-profiles.md": "6568ca29b6ee00d8",
   "gsd-core/references/mvp-concepts.md": "3464783eaaef5c10",
   "gsd-core/references/phase-argument-parsing.md": "e5bbb985f3bc3e34",
   "gsd-core/references/planner-antipatterns.md": "2459c40bfc8a0ea8",
@@ -277,13 +277,13 @@
   "gsd-core/workflows/autonomous.md": "6cb0c014f5f56965",
   "gsd-core/workflows/check-todos.md": "6526b64ee88c7d2e",
   "gsd-core/workflows/cleanup.md": "94d771d26f62dc86",
-  "gsd-core/workflows/code-review-fix.md": "5d97b960da4fef73",
-  "gsd-core/workflows/code-review.md": "aec8ef4de1829607",
+  "gsd-core/workflows/code-review-fix.md": "adb9388bb157610c",
+  "gsd-core/workflows/code-review.md": "ae6bcbd1575aeec4",
   "gsd-core/workflows/complete-milestone.md": "614299b2c08e66c3",
   "gsd-core/workflows/debug.md": "9d4a8afc8d36be93",
   "gsd-core/workflows/diagnose-issues.md": "2971c699d52f1b85",
   "gsd-core/workflows/discovery-phase.md": "724408336596c50c",
-  "gsd-core/workflows/discuss-phase-assumptions.md": "310b08dc31710cbc",
+  "gsd-core/workflows/discuss-phase-assumptions.md": "92e43cd12200c610",
   "gsd-core/workflows/discuss-phase-power.md": "5c0d1ca6abda0383",
   "gsd-core/workflows/discuss-phase.md": "3a62a8d4c374c69f",
   "gsd-core/workflows/discuss-phase/modes/advisor.md": "83ca3ea4fac785af",
@@ -349,7 +349,7 @@
   "gsd-core/workflows/pr-branch.md": "929b7cb0c99c7b9e",
   "gsd-core/workflows/profile-user.md": "248d59a31948e0ed",
   "gsd-core/workflows/progress.md": "8fc3404087f50b95",
-  "gsd-core/workflows/quick.md": "10cc8ddd4bc3f0ee",
+  "gsd-core/workflows/quick.md": "9bdccb7c6a5530c9",
   "gsd-core/workflows/reapply-patches.md": "a0e9b53f90abceb2",
   "gsd-core/workflows/remove-phase.md": "dea4661e8f89596f",
   "gsd-core/workflows/remove-workspace.md": "446847e71aa52504",