fix: dynamic frameworkLogger import + server static file fixes

[htafolla]

Problem

OpenCode TUI renders a blank black screen on launch due to a broken import in the codex injection plugin.

Root cause: PR #12 replaced console.warn with frameworkLogger.log() but used a static import path ../core/framework-logger.js that only resolves correctly from dist/plugin/. When the compiled plugin is loaded from .opencode/plugins/ (where OpenCode discovers it), the relative path resolves to .opencode/core/ — which doesn't exist. Bun throws ERR_MODULE_NOT_FOUND and OpenCode silently fails to initialize.

Changes

Plugin (src/plugin/strray-codex-injection.ts)

• Replaced static frameworkLogger import with dynamic loader + noop fallback
• Uses the same ../../dist/core/ → ../core/ candidate-path pattern already used by loadConfigPaths() and importSystemPromptGenerator()
• Plugin works from both dist/plugin/ and .opencode/plugins/ without modification

Server (src/cli/server.ts)

• Fixed PUBLIC_DIR to resolve to project-root/public/ (was dist/public/ which doesn't exist at runtime)
• Added 404 guard on sendFile for index.html
• Moved error handler middleware before app.listen() so Express actually registers it
• Replaced console.error with frameworkLogger

Build (package.json)

• Build script now copies public/* to dist/public/

Verification

• npm test — 2399 tests passing
• opencode debug config --print-logs --log-level DEBUG — no ERROR lines, plugin loads successfully
• bun -e "import('./.opencode/plugins/strray-codex-injection.js')" — loads OK

[htafolla]

Superseded by PRs #25 (init.sh fallback), #26 (Docker import resolution), and subsequent merges. The dynamic frameworkLogger import pattern was reimplemented better in #26 with import.meta.url + Docker-aware path resolution. Server static file fixes were already applied independently.