chore(release): 0.6.8

[willytop8]

Summary

Prepare opencode-goal-plugin@0.6.8 for the same-session process-contention
fix merged in #46 (issue #41).

Changes

• bump package.json and package-lock.json from 0.6.7 to 0.6.8
• date the existing issue Gracefully handle contested persistence lock when running multiple instances #41 changelog entries as 0.6.8 — 2026-08-01
• keep the release commit limited to those three metadata files

No source or README change is introduced by this PR. The implementation,
documentation, and tests were reviewed and merged in #46.

Impact

• A second OpenCode process opening the same session remains usable for
  ordinary chat and unrelated tools instead of failing plugin initialization.
• Goal commands, goal tools, persistence, and auto-continuation stay safely
  passive while another process owns that session shard.
• A fresh explicit goal command or tool can take ownership after the owner
  exits and reload the recovered goal paused.
• Immutable owner claims and an atomic compatibility guard prevent stale
  cleanup, simultaneous reclaim, delayed publication, and mixed-version
  startup races from creating two owners or deleting a replacement lease.

Validation

• npm ci — passed; 3 packages audited, 0 vulnerabilities
• npm run release:check — passed
  • 329/329 tests
  • 64/64 critical mutants killed
  • behavior benchmark 100/100
  • 98.35% line, 90.41% branch, and 89.22% function coverage
  • type, source smoke, packed-host, packed-tool, verifier, production audit,
    and package-content gates passed
• exact issue-fix merge CI and CodeQL passed on Linux, macOS, and Windows
• real OpenCode acceptance passed on 1.17.15 and 1.18.11
• reviewed local package: 24 files, 109,706 bytes packed, SHA-256
  a0679f0669fa3bdddeb0b0196bb4cf0e0e002a45b0e55c7a255a0bd1e1dd16f7
• clean consumer installation, six-check verifier, and public root/server
  imports passed from that exact tarball

Checklist

• Version metadata updated together
• Changelog dated without rewriting the reviewed entries
• Full local release gate passed
• Exact tarball contents and installed behavior inspected
• No source, README, or breaking API change in this release commit