feat: community-requested commands — /gsd:review, /gsd:plant-seed, /gsd:pr-branch

Three commands reimplemented from positively-received community PRs:

1. /gsd:review (#925) — Cross-AI peer review
   Invoke external AI CLIs (Gemini, Claude, Codex) to independently
   review phase plans. Produces REVIEWS.md with per-reviewer feedback
   and consensus summary. Feed back into planning via --reviews flag.
   Multiple users praised the adversarial review concept.

2. /gsd:plant-seed (#456) — Forward-looking idea capture
   Capture ideas with trigger conditions that auto-surface during
   /gsd:new-milestone. Seeds preserve WHY, WHEN to surface, and
   breadcrumbs to related code. Better than deferred items because
   triggers are checked, not forgotten.

3. /gsd:pr-branch (#470) — Clean PR branches
   Create a branch for pull requests by filtering out .planning/
   commits. Classifies commits as code-only, planning-only, or mixed,
   then cherry-picks only code changes. Reviewers see clean diffs.

All three are standalone command+workflow additions with no core code
changes. Help workflow updated. Test skill counts updated.

797/797 tests pass.

commands/gsd/plant-seed.md

@@ -0,0 +1,28 @@
+---
+name: gsd:plant-seed
+description: Capture a forward-looking idea with trigger conditions — surfaces automatically at the right milestone
+argument-hint: "[idea summary]"
+allowed-tools:
+  - Read
+  - Write
+  - Edit
+  - Bash
+  - AskUserQuestion
+---
+
+<objective>
+Capture an idea that's too big for now but should surface automatically when the right
+milestone arrives. Seeds solve context rot: instead of a one-liner in Deferred that nobody
+reads, a seed preserves the full WHY, WHEN to surface, and breadcrumbs to details.
+
+Creates: .planning/seeds/SEED-NNN-slug.md
+Consumed by: /gsd:new-milestone (scans seeds and presents matches)
+</objective>
+
+<execution_context>
+@~/.claude/get-shit-done/workflows/plant-seed.md
+</execution_context>
+
+<process>
+Execute the plant-seed workflow from @~/.claude/get-shit-done/workflows/plant-seed.md end-to-end.
+</process>

commands/gsd/pr-branch.md

@@ -0,0 +1,25 @@
+---
+name: gsd:pr-branch
+description: Create a clean PR branch by filtering out .planning/ commits — ready for code review
+argument-hint: "[target branch, default: main]"
+allowed-tools:
+  - Bash
+  - Read
+  - AskUserQuestion
+---
+
+<objective>
+Create a clean branch suitable for pull requests by filtering out .planning/ commits
+from the current branch. Reviewers see only code changes, not GSD planning artifacts.
+
+This solves the problem of PR diffs being cluttered with PLAN.md, SUMMARY.md, STATE.md
+changes that are irrelevant to code review.
+</objective>
+
+<execution_context>
+@~/.claude/get-shit-done/workflows/pr-branch.md
+</execution_context>
+
+<process>
+Execute the pr-branch workflow from @~/.claude/get-shit-done/workflows/pr-branch.md end-to-end.
+</process>

commands/gsd/review.md

@@ -0,0 +1,37 @@
+---
+name: gsd:review
+description: Request cross-AI peer review of phase plans from external AI CLIs
+argument-hint: "--phase N [--gemini] [--claude] [--codex] [--all]"
+allowed-tools:
+  - Read
+  - Write
+  - Bash
+  - Glob
+  - Grep
+---
+
+<objective>
+Invoke external AI CLIs (Gemini, Claude, Codex) to independently review phase plans.
+Produces a structured REVIEWS.md with per-reviewer feedback that can be fed back into
+planning via /gsd:plan-phase --reviews.
+
+**Flow:** Detect CLIs → Build review prompt → Invoke each CLI → Collect responses → Write REVIEWS.md
+</objective>
+
+<execution_context>
+@~/.claude/get-shit-done/workflows/review.md
+</execution_context>
+
+<context>
+Phase number: extracted from $ARGUMENTS (required)
+
+**Flags:**
+- `--gemini` — Include Gemini CLI review
+- `--claude` — Include Claude CLI review (uses separate session)
+- `--codex` — Include Codex CLI review
+- `--all` — Include all available CLIs
+</context>
+
+<process>
+Execute the review workflow from @~/.claude/get-shit-done/workflows/review.md end-to-end.
+</process>