feat(dashboard): nav restructure, full context-help coverage, 11 new ref docs

Navigation:
- New order: Overview · Todo · Domains · Repos · Workstreams (collapsible,
  open:false, with atomic sub-entries: Decisions, Tasks, Debt, Extends,
  Dependencies) · Contributions · SBOM · Progress · Reference (collapsible)
- Reference section gains path:/reference landing page; all 18 doc pages
  listed in nav (alphabetical) and in reference.md table

New pages:
- todo.md — Internal / Ecosystem / Third-party todo classification
- dependencies.md — dependency edge table derived from state/summary
- reference.md — Reference landing page with full doc index

New reference doc pages (11):
  contributions, debt, dependencies, domains, extensions, overview,
  repos, tasks, todo + reference (meta) already added previously

doc-overlay.js — lazy bubblehelp tooltip:
- _titleCache Map + _fetchDocTitle(docPath): on first hover of any ?
  button, fetches the target doc page, parses <h1>, sets btn.title
- Native browser tooltip appears exactly on the ? circle on subsequent hover

Context-help wired on all 14 dashboard pages:
- h1 withDocHelp added to: index, todo, domains, repos, tasks, techdept,
  extensions, dependencies (contributions/workstreams/decisions/sbom/
  progress/reference were already wired)
- domains.md + repos.md: added missing withDocHelp import and live-data link
- tasks/techdept/extensions: removed duplicate _h1 const that caused
  SyntaxError: Identifier '_h1' has already been declared

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

state-hub/dashboard/src/docs/todo.md

@@ -0,0 +1,71 @@
+---
+title: Todo — Reference
+---
+
+# Todo — Reference
+
+The Todo page shows the Custodian's own open work items classified by where the
+work belongs — inside this repo, routed from another ecosystem repo, or aimed
+at an upstream third-party project.
+
+This page is the session-start orientation surface for the `the-custodian` repo.
+See [Inter-Repo Communication](/docs/inter-repo-communication) for the full
+boundary rule and routing workflows.
+
+---
+
+## The three classes
+
+### Internal
+
+Open tasks (`todo`, `in_progress`, `blocked`) in **custodian domain workstreams**
+whose title does not contain a `[repo:]` routing prefix.
+
+These are tasks this agent is directly responsible for and can address within
+the current repo.
+
+### Ecosystem (inbound)
+
+Tasks from **any workstream** whose title contains `[repo:the-custodian]`.
+
+These tasks were created by agents in other repos to route work to the custodian.
+When a task with this prefix appears, the session protocol picks it up, the
+custodian creates a workplan file (ADR-001), and addresses the work here.
+
+### Third-party (outbound)
+
+Contribution artifacts in **open status** (`draft`, `submitted`, `acknowledged`).
+
+These represent work the custodian has identified for upstream repos it does not
+own. They remain on the todo list until the upstream loop is closed (`merged`,
+`rejected`, or `withdrawn`).
+
+---
+
+## Classification decision table
+
+| Situation | Class | Action |
+|-----------|-------|--------|
+| Bug found in this repo | Internal | Fix it directly |
+| Work needed in another registered repo | Ecosystem | `create_task(..., title="[repo:<slug>] ...")` |
+| Bug found in an upstream library | Third-party | Create BR artifact + `register_contribution` |
+| Feature needed from upstream | Third-party | Create FR artifact + `register_contribution` |
+
+---
+
+## KPI sidebar card
+
+Shows the count of open items in each class at a glance. The `?` button links
+to this reference page.
+
+---
+
+## Data sources
+
+Polls every **15 seconds**:
+- `GET /tasks/?limit=500` — all tasks
+- `GET /workstreams/` — for domain + title context
+- `GET /topics/` — for domain slug resolution
+- `GET /contributions/` — for third-party todos
+
+*Classification is done client-side — no server-side filter endpoint required.*