Plugin Docs: Resolve relative asset paths from doc file directory

[sunker]

What this PR does / why we need it:

Adds an optional file parameter to parseMarkdown so relative image srcs resolve from the doc file's directory rather than the docs root. Switches to URL-based resolution via new URL(), which handles ./, ../ and trailing slashes without per-caller logic.

The CLI dev server now passes { assetBaseUrl: '/', file: page.file } so local preview exercises the same rewrite code path as production.

Side effect of switching to new URL(): srcs containing ./ or ../ segments are now normalized in the output (e.g. base/../img/y.png → base/img/y.png) instead of being passed through literally. The literal-segment behavior was technically broken anyway, so this is a quiet correctness improvement, not a regression.

Which issue(s) this PR fixes:

No issue - part of the multi-page plugin docs initiative. Marketing-website consumer change to follow.

📦 Published PR as canary version: Canary Versions

✨ Test out this PR locally via:

npm install website@5.5.4-canary.2611.25323306221.0
npm install @grafana/create-plugin@7.3.1-canary.2611.25323306221.0
npm install @grafana/plugin-docs-cli@0.0.11-canary.2611.25323306221.0
npm install @grafana/plugin-docs-parser@0.0.5-canary.2611.25323306221.0
# or 
yarn add website@5.5.4-canary.2611.25323306221.0
yarn add @grafana/create-plugin@7.3.1-canary.2611.25323306221.0
yarn add @grafana/plugin-docs-cli@0.0.11-canary.2611.25323306221.0
yarn add @grafana/plugin-docs-parser@0.0.5-canary.2611.25323306221.0

[github-actions]

Hello! 👋 This repository uses Auto for releasing packages using PR labels.

✨ This PR can be merged and will trigger a new patch release.
NOTE: When merging a PR with the release label please avoid merging another PR. For further information see here.

[Copilot]

Pull request overview

This PR improves plugin docs asset URL rewriting by letting the parser resolve relative image/asset paths from the current doc file’s directory (instead of always from the docs root), using URL-style resolution semantics. It also updates the CLI dev server to use the same rewriting path as production by passing a root-relative assetBaseUrl.

Changes:

• Add optional file context to asset rewriting so img/... resolves relative to the markdown file’s directory.
• Switch asset path rewriting to new URL() resolution (normalizing ./ and ../ segments).
• Update the CLI docs dev server (and tests/fixtures) to pass { assetBaseUrl: '/', file: page.file } and validate the behavior.

Reviewed changes

Copilot reviewed 6 out of 7 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
packages/plugin-docs-parser/src/plugins/rehype-rewrite-asset-paths.ts	Introduces URL-based resolver + optional file context for per-page asset resolution.
packages/plugin-docs-parser/src/plugins/rehype-rewrite-asset-paths.test.ts	Adds coverage for per-page resolution and root-relative base behavior.
packages/plugin-docs-parser/src/parser.ts	Plumbs new file option through parseMarkdown to the rehype plugin.
packages/plugin-docs-cli/src/server/server.ts	Uses parser asset rewriting during local preview with assetBaseUrl: '/' and file: page.file.
packages/plugin-docs-cli/src/server/server.test.ts	Adds an integration test asserting correct per-directory image resolution in CLI output.
packages/plugin-docs-cli/src/fixtures/test-docs/config/database.md	Adds relative-image examples used by the new CLI server test.