docs: add [Unreleased] section and #4225 known issue

CHANGELOG.md:
- Remove the stale [4.2.1] - Unreleased section (4.2.1 has shipped).
- Add [Unreleased] (next-minor or 4.3.0) covering all 240 unpublished
  commits, grouped by user impact rather than commit type.
  - Added: default_mode, i18n en/zh, disabled_providers,
    plan-format-validator, Prometheus spec-driven mode, per-agent skill
    filtering, look_at async, keyword-detector.enabled_expansions,
    tui-plugin doctor check, taskCleanupDelayMs, agent displayName i18n,
    Grok reasoningEffort, CLI setup alias.
  - Changed: 8-package layering refactor, model-core DI,
    prompt-async-gate modularization, additive OpenCode config dir,
    delegate_task defaults.
  - Fixed: background-agent stability, team-mode hardening, runtime
    fallback, Windows/WSL/MSYS2, tmux-subagent, skill-mcp survival,
    slash-command dedup, hyperplan .hpp false positive, todo
    continuation loop, tool.definition wiring, model parser guards,
    mcp_ prefix strip, prompt-shield XML tag, glob/grep symlink
    tolerance, chat-message cache refresh, skill short names, process
    cleanup.
  - Fixed in this release gate: the pre-publish review findings -
    notepad-guard wire+.omo, i18n init wire, start-work .omo affinity,
    default_mode ultrawork+ralph priority, multimodal-looker prompt
    alignment, delegate-task per-agent skill enforcement, model-core
    server_error pattern restore.
- Update footer comparison links: [Unreleased] points at v4.2.3...HEAD,
  [4.2.3] corrected to v4.2.2...v4.2.3.

docs/reference/known-issues.md:
- Add #4225: custom LSP config in .opencode/oh-my-openagent.jsonc is
  silently ignored after the LSP->MCP migration. Captures symptom,
  workaround, and the upstream tracking issue.

docs/reference/known-issues.md

@@ -31,3 +31,10 @@ The original failure-mode the PR targets remains in v4.2.0.
 ### Tracking
 
 Issue #4059 tracks the reland with stabilized regression coverage. The reland is deferred to a follow-up release and should account for current schema-shape changes plus prompt-async-gate semantics.
+
+## #4225 — Custom LSP config in `.opencode/oh-my-openagent.jsonc` is silently ignored
+
+- **Affects**: v4.2.3+ after the LSP to MCP migration.
+- **Symptom**: Custom LSP server configuration in your project's `oh-my-openagent.jsonc` is not applied at runtime.
+- **Workaround**: Configure your LSP server through OpenCode's native `lsp` config instead.
+- **Status**: Open. Tracked at https://github.com/code-yeongyu/oh-my-openagent/issues/4225.