feat: resizable viewport

[ktsn]

It does not have any styles yet. I'll add them later.

[codecov]

Codecov Report

Merging #19 into master will increase coverage by 1.16%.
The diff coverage is 68.29%.

@@            Coverage Diff             @@
##           master      #19      +/-   ##
==========================================
+ Coverage   63.48%   64.64%   +1.16%     
==========================================
  Files          41       44       +3     
  Lines        1320     1355      +35     
  Branches      314      324      +10     
==========================================
+ Hits          838      876      +38     
+ Misses        467      464       -3     
  Partials       15       15

Impacted Files	Coverage Δ
src/view/App.vue	0% <ø> (ø)	⬆️
src/view/components/PageMain.vue	0% <0%> (ø)	⬆️
src/view/store/modules/viewport.ts	0% <0%> (ø)
src/view/components/Viewport.vue	0% <0%> (ø)	⬆️
src/view/components/Renderer.vue	0% <0%> (ø)	⬆️
src/view/store/modules/index.ts	0% <0%> (ø)	⬆️
src/view/components/Resizable.vue	100% <100%> (ø)
src/view/store/modules/project.ts	47.26% <100%> (+7.67%)	⬆️
src/view/components/Toolbar.vue	90% <90%> (ø)
... and 4 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 8ca762b...825a2d9. Read the comment docs.

[ktsn]

TODO: add a toolbar for the users can see the current viewport size.

[ktsn]