fix(#2285): wire claude-orchestration Workflow backend into execute-phase (#2314)

The claude-orchestration capability (#1143) shipped registered 'active'
but fully inert: detectWorkflowBackend/emitWorkflowScript had no caller
outside their own CLI router, and execute-phase.md declared an
execute:wave:pre hook point that the workflow body never rendered — so
claude_orchestration.enabled:true had zero effect on real runs.

Approach B (maintainer-chosen):
- execute-phase.md now renders the execute:wave:pre hook
  (gsd_run loop render-hooks execute:wave:pre) at a new step 2.75,
  immediately before each wave's Agent() dispatch — fixing the latent
  dead-hook gap for any pre-wave capability.
- Move the claude-orchestration contribution execute:wave:post ->
  execute:wave:pre (a pre-wave backend selector belongs before dispatch,
  not after); rename fragments/execute-wave-post.md -> execute-wave-pre.md
  with prose instructing the orchestrator to call resolve-wave-dispatch
  before step 3. Unrelated wave:post contributions (ui.safety-gate, drift,
  external-job, mempalace) untouched.
- New .cts seam resolveWaveDispatch(input) composes detectWorkflowBackend
  + emitWorkflowScript into one {backend:'inline'|'workflow', ...} result;
  exposed as gsd-tools claude-orchestration resolve-wave-dispatch. This is
  a real non-CLI-router, non-test caller of both functions.

Fail-closed: any gate miss (disabled, non-Claude runtime, Workflow tool
absent, SDK below floor, execution_backend:inline, malformed input) or an
emit failure resolves to inline with a byte-identical result shape — no
regression to the default-off execute-phase path.

Regression tests (tests/fix-2285-*) cover happy-path activation + SDK-floor
BVA, the fail-closed gate-miss table with detectWorkflowBackend parity, a
fast-check composition property, capability.json contribution assertions,
and a source-contract guard that execute:wave:pre is now actually rendered.
Dependent registry-shape assertions updated in-scope.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

gsd-core/workflows/execute-phase.md

@@ -115,7 +115,7 @@ fi
 ```
 `isolation="worktree"` is a Claude-Code-specific agent primitive; no other runtime can honor it (Codex maps subagents to `spawn_agent`, others prohibit or omit worktree binding). Failing closed prevents main-checkout edits while the workflow believes agents are isolated.
 
-If the project uses git submodules, worktree isolation is unsafe **only when a plan touches a submodule path** — the executor commit protocol cannot correctly handle submodule commits inside isolated worktrees. The previous behavior unconditionally disabled worktree isolation whenever `.gitmodules` existed, which penalised every plan in a submodule project even when the plan was nowhere near a submodule. Compute submodule paths once and intersect them per-plan with the plan's declared `files_modified` frontmatter.
+If the project uses git submodules, worktree isolation is unsafe **only when a plan touches a submodule path** — the executor commit protocol cannot correctly handle submodule commits inside isolated worktrees. Compute submodule paths once and intersect them per-plan with the plan's declared `files_modified` frontmatter.
 
 ```bash
 # Parse submodule paths from .gitmodules once (empty if no .gitmodules).
@@ -277,12 +277,6 @@ checkpoints between tasks. The user can review, modify, or redirect work at any
 
 3. After all plans: proceed to verification (same as normal mode).
 
-**Benefits of interactive mode:**
-- No subagent overhead — dramatically lower token usage
-- User catches mistakes early — saves costly verification cycles
-- Maintains GSD's planning/tracking structure
-- Best for: small phases, bug fixes, verification gaps, learning GSD
-
 **Skip to handle_branching step** (interactive plans execute inline after grouping).
 </step>
 
@@ -553,7 +547,7 @@ increases monotonically across waves. `{status}` is `complete` (success),
    ```
 
    - Bad: "Executing terrain generation plan"
-   - Good: "Procedural terrain generator using Perlin noise — creates height maps, biome zones, and collision meshes. Required before vehicle physics can interact with ground."
+   - Good: "Procedural terrain generator using Perlin noise — creates height maps and biome zones. Required before vehicle physics."
 
 2.5. **Per-plan worktree decision (run for each plan in this wave BEFORE its dispatch):**
 
@@ -561,6 +555,14 @@ increases monotonically across waves. `{status}` is `complete` (success),
 
    The dispatch branches in step 3 below MUST gate on `USE_WORKTREES_FOR_PLAN` for the current plan, not on the project-level `USE_WORKTREES`.
 
+2.75. **Execute:wave:pre capability dispatch:**
+
+   ```bash
+   WAVE_PRE_HOOKS_JSON=$(gsd_run loop render-hooks execute:wave:pre --raw)
+   ```
+
+   If a contribution's `activeHooks` entry provides an alternate wave dispatch, follow it instead of step 3's inline loop; otherwise proceed to step 3.
+
 3. **Spawn executor agents:**
 
    **Emit a plan-start heartbeat (literal line, no tool call) immediately before