feat: update project version, enhance PluginApiClient options, and add new extension point interfaces

[pikann]

This pull request bumps the package version, fixes a broken CD publish step, tweaks PluginApiClient to support pages with no current project, and adds two new full-page extension points.

CI/CD:

• Bumped the CD workflow's Node.js version from 20 to 24.
• Pinned npm to the 11.x line instead of npm@latest — npm 12.0.0 has a packaging bug where libnpmpublish requires sigstore but the published tarball is missing it, crashing npm publish --provenance with "Cannot find module 'sigstore'" (see npm/cli#9722).

Release:

• Bumped package.json version from 0.1.0 to 0.3.0.

PluginApiClient changes:

• projectId is now optional on PluginApiClientOptions, defaulting to "", so the client can be constructed for admin/global-scope pages that have no current project (callers must not call listTasks/getTask/getProject/listMembers in that case).
• listTasks now defaults page_size to the host's max (200) instead of leaving it unset (which fell back to the host's default of 20), matching how most callers use it — an unfiltered "get the project's tasks" lookup.
• listTasks and listMembers were updated to match the host API's actual response envelope ({ items: [...] } for tasks, a bare array for members) instead of the previously assumed { tasks: [...] } / { members: [...] } shapes.

New extension points:

• Added project.page — a full-bleed page routed from a nav item the plugin registers in the project sidebar, for plugin features that deserve their own page rather than a settings tab (e.g. a project-wide time-tracking view).
• Added admin.page — a full-bleed page routed from a nav item in the admin sidebar, gated behind the users.write global permission, for cross-project/instance-wide plugin views (e.g. total logged time across all projects). Its injected api client has no projectId.
• Exported ProjectPageProps and AdminPageProps from src/index.ts and added both to the ExtensionPointProps union.