feat(voyage)!: marketplace handoff — rename plugins/ultraplan-local to plugins/voyage [skip-docs]

Session 5 of voyage-rebrand (V6). Operator-authorized cross-plugin scope.

- git mv plugins/ultraplan-local plugins/voyage (rename detected, history preserved)
- .claude-plugin/marketplace.json: voyage entry replaces ultraplan-local
- CLAUDE.md: voyage row in plugin list, voyage in design-system consumer list
- README.md: bulk rename ultra*-local commands -> trek* commands; ultraplan-local refs -> voyage; type discriminators (type: trekbrief/trekreview); session-title pattern (voyage:<command>:<slug>); v4.0.0 release-note paragraph
- plugins/voyage/.claude-plugin/plugin.json: homepage/repository URLs point to monorepo voyage path
- plugins/voyage/verify.sh: drop URL whitelist exception (no longer needed)

Closes voyage-rebrand. bash plugins/voyage/verify.sh PASS 7/7. npm test 361/361.

plugins/voyage/CONTRIBUTING.md

@@ -0,0 +1,59 @@
+# Contributing to trekplan
+
+This is a solo project. Issues are welcome. PRs may be considered but are not expected.
+
+## Reporting bugs
+
+Open an issue with:
+- Plugin version (from `.claude-plugin/plugin.json`)
+- Claude Code version (`claude --version`)
+- What you did, what you expected, what happened instead
+- Whether it fails consistently or occasionally
+
+## Suggesting features or improvements
+
+Open an issue describing:
+- The problem you ran into
+- What you think would solve it
+- Any alternatives you considered
+
+## Design principles
+
+Changes to this plugin must preserve:
+- **Pure markdown** — no scripts, no dependencies, no platform-specific code
+- **Cross-platform** — must work identically on Mac, Linux, and Windows
+- **Cost-aware** — Sonnet for exploration, Opus only for planning
+- **Privacy-first** — never read files outside the repo, never log secrets
+- **Honest** — if a task is trivial, say so instead of inflating the plan
+
+## Architecture
+
+| File | Purpose |
+|------|---------|
+| `.claude-plugin/plugin.json` | Plugin manifest |
+| `commands/trekresearch.md` | The `/trekresearch` slash command — research orchestration |
+| `commands/trekplan.md` | The `/trekplan` slash command — planning orchestration |
+| `commands/trekexecute.md` | The `/trekexecute` slash command — execution orchestration |
+| `agents/*.md` | 19 specialized agents for research, exploration, review, and orchestration |
+| `templates/plan-template.md` | Structured plan output format |
+| `templates/research-brief-template.md` | Research brief format with triangulation and confidence |
+| `templates/spec-template.md` | Spec file format |
+| `templates/session-spec-template.md` | Session spec format for headless execution |
+| `templates/headless-launch-template.md` | Launch script template |
+
+The command files are the core. All logic lives in markdown.
+
+## Testing locally
+
+```bash
+claude --plugin-dir /path/to/trekplan
+# Then in the session:
+/trekresearch <research question>
+/trekplan <describe a task>
+/trekexecute <path to plan>
+```
+
+Verify:
+- `/trekresearch`: Research agents spawn, brief written to `.claude/research/`
+- `/trekplan`: Exploration agents spawn in parallel, plan follows template, plan written to `.claude/plans/`, adversarial review runs
+- `/trekexecute`: Steps execute with verify + checkpoint per step