Adoption: replace Plannotator monorepo's local copy with this package

[backnotprop]

Tracking adoption of this package in the Plannotator monorepo (backnotprop/plannotator), replacing the local copy that shipped with backnotprop/plannotator#890. Umbrella feature: backnotprop/plannotator#887.

Preconditions

• feat(editor): markdown edit mode — direct document editing with diff-to-agent feedback backnotprop/plannotator#890 merged (self-contained local copy; zero references to this package by design)
• @plannotator/markdown-editor@0.1.0 published to npm (pnpm publish — prepublishOnly runs all gates)

Integration PR (monorepo)

• bunfig.toml: add "@plannotator/markdown-editor" to minimumReleaseAgeExcludes (repo policy blocks packages <7 days old; same exception as @pierre/diffs)
• bun add @plannotator/markdown-editor in packages/ui
• Shrink packages/ui/components/MarkdownEditor.tsx to a theme-bridging shim: calls useTheme() (the provider is rendered inside App's JSX, so App's body can't), passes mode to the package component, maps gridEnabled → cardClassName. App.tsx import line stays unchanged.
• Replace local markdown-editor.css with @plannotator/markdown-editor/themes/plannotator.css
• Diff-before-delete: verify package source is byte-equivalent to the local copy (CSS variable declarations, light-mode block, code-languages array) before removing anything
• Gates: fidelity corpus test (150-plan sample), full build chain, bundle delta recorded (~0 expected), dev-server visual check in dark AND light mode

After

• Package is the single source of truth: PFM syntax decorations (callouts, wiki-links, code-file links) land here as CM6 extensions, monorepo consumes via version bumps
• Workspaces (enterprise) adopts with its own theme mapping

[backnotprop]

Progress:

• @plannotator/markdown-editor@0.1.0 published to npm (all gates ran via prepublishOnly)
• Integration folded directly into feat(editor): markdown edit mode — direct document editing with diff-to-agent feedback backnotprop/plannotator#890 (commit d12e2054) rather than a follow-up PR — the local copy never lands on main
• bunfig exception, theme-bridging shim, diff-verified CSS deletion, all gates green (fidelity 4/4, build delta +0.4 KB)

Remaining: merge #890. After that this package is the single source of truth for editor work.

[backnotprop]

Adoption complete in backnotprop/plannotator#890 (commit d12e2054): package consumed via shim, bunfig exception in place, local copy deleted, all gates green. Merging that PR is the only remaining step and it's tracked there.