fix: drop Home's end-of-list marker, word each empty view for its tab

[vibhavkatre]

Home closed every populated view with:

You've reached the end · made with Frappe Draw

It told the user nothing they could act on, and anyone who met it before scrolling
read it as an empty state. It is gone.

The empty views carry the message instead

Each is now worded for its own tab, because "empty" means something different in
each one:

Tab	Title	Hint
Home	Start a drawing	Use Create to make your first one.
Recent	Nothing recent	Diagrams you open show up here.
Shared with you	Nothing shared with you	Diagrams others share with you show up here.
Pinned	No pinned diagrams	Pin a diagram to keep it handy here.

Home is the only one that reads as an invitation rather than a report. The Create
button is right there, and a first-time user lands on it with nothing.

A search that matches nothing still wins over the tab wording, since the query is
what excluded the rows — "No pinned diagrams" would be wrong when the tab does have
pins.

Where the copy lives

The set moves to homeViews.js, next to the nav and the view titles, so it is
unit-testable without mounting the grid. That is the reason the module exists:

Kept in one plain module — not inside the SFCs — so the sidebar / shell / grid
stay declarative and the unit tests can assert the view set and filters without
mounting (browser-free) components.

An unknown mode falls back to Home rather than rendering an undefined icon. A test
walks the nav set and fails if a view is ever added without an empty state.

Verification

Driven live on Home:

• a populated Home no longer ends with the marker

• the Shared tab, with nothing in it, shows its own wording

• a search matching nothing says "No diagrams match", not the tab wording

• yarn test — 879 pass, 8 new checks

• yarn build — clean

Closes #220