refactor(web): split app.js into per-view modules + shared UI helpers

[smochan]

Summary

Track A2, stacked on #69. Pure extraction, zero behavior change:

• app.js: 919 → 240 lines — keeps only data fetch, render dispatcher, sidebar/theme shell
• 6 new view modules (views/overview|hld|flows|matrix|sankey|treemap.js) exposed via window.CGViews.*
• ui/helpers.js: shared esc/format/tooltip/toast/mermaid-theme/kind helpers via window.CGUI.* with per-view destructuring (matches the repo's no-bundler script-tag architecture)
• index.html loads helpers → views → app.js in dependency order; no-CDN guard test extended to the new files

Implemented by a Sonnet subagent against a Fable spec; reviewed (namespace wiring, window.state exposure, node --check on every file, payload smoke test) by the orchestrating session.

Test plan

• Full suite 708 passed; ruff + mypy clean
• node --check on all new/changed JS
• Dashboard payload smoke test on a fresh tiny repo

🤖 Generated with Claude Code

---

Recreated from #70 (auto-closed when its stacked base branch was deleted during the merge train).

[github-actions]

codegraph PR review

Diff vs main · severity ≤ high

codegraph review (target: main)

Diff: +20 / -22 / ~0 nodes, +120 / -305 edges

Findings (4)

severity	rule	kind	qualname	file:line	score	message
critical	removed-referenced	graph	codegraph.web.static.app.esc	codegraph/web/static/app.js:864	50	Removed symbol still referenced by callers
critical	removed-referenced	graph	codegraph.web.static.app.mermaidThemeVars	codegraph/web/static/app.js:65	50	Removed symbol still referenced by callers
critical	removed-referenced	graph	codegraph.web.static.app.pyvisHref	codegraph/web/static/app.js:799	50	Removed symbol still referenced by callers
low	new-dead-code	graph	codegraph.web.static.views.flows._selectFlow	codegraph/web/static/views/flows.js:54	10	Potentially unreachable new code

_{Triggered by codegraph CI · last run}

[github-actions]

codegraph PR review

Diff vs main · severity ≤ high

codegraph review (target: main)

Diff: +20 / -22 / ~0 nodes, +120 / -305 edges

Findings (4)

severity	rule	kind	qualname	file:line	score	message
critical	removed-referenced	graph	codegraph.web.static.app.esc	codegraph/web/static/app.js:864	50	Removed symbol still referenced by callers
critical	removed-referenced	graph	codegraph.web.static.app.mermaidThemeVars	codegraph/web/static/app.js:65	50	Removed symbol still referenced by callers
critical	removed-referenced	graph	codegraph.web.static.app.pyvisHref	codegraph/web/static/app.js:799	50	Removed symbol still referenced by callers
low	new-dead-code	graph	codegraph.web.static.views.flows._selectFlow	codegraph/web/static/views/flows.js:54	10	Potentially unreachable new code

_{Triggered by codegraph CI · last run}

[github-actions]

codegraph PR review

Diff vs main · severity ≤ high

codegraph review (target: main)

Diff: +36 / -22 / ~0 nodes, +307 / -305 edges

Findings (1)

severity	rule	kind	qualname	file:line	score	message
high	new-untested-hotspot	graph	codegraph.web.static.ui.helpers.CGUI.formatQn	codegraph/web/static/ui/helpers.js:22	0	New function with 5 callers and no test coverage

_{Triggered by codegraph CI · last run}