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>

dashboard/src/docs/overview.md

@@ -0,0 +1,84 @@
+---
+title: Overview — Reference
+---
+
+# Overview — Reference
+
+The Overview page is the operational home screen of the Custodian State Hub.
+It shows the live health of the entire ecosystem at a glance — active work,
+blocking decisions, and system-derived next-step suggestions.
+
+---
+
+## Sections
+
+### Open Workstreams by Domain
+
+A horizontal stacked bar chart showing every active workstream across all six
+domains. Each bar is broken into four task-status segments:
+
+| Colour | Segment |
+|--------|---------|
+| green | done |
+| blue | in progress |
+| orange-red | blocked |
+| light grey | todo |
+
+The left axis shows domain labels (one per group of workstreams). The `done/total`
+count is printed to the right of each bar. Workstreams with no tasks yet show
+a grey "— no tasks yet" label.
+
+### Contribution & SBOM Health
+
+Three summary cards linked to the Contributions and SBOM pages:
+
+| Card | Shows |
+|------|-------|
+| **Contributions** | Total artifact count; orange warning if any are awaiting upstream response |
+| **Licence Risk** | Count of SBOM packages with copyleft licences in direct dependencies |
+| **SBOM** | Breakdown by contribution type (BR / FR / EP / UPR) |
+
+### Status
+
+Four metric cards:
+
+| Card | Meaning |
+|------|---------|
+| **Active Workstreams** | Count of non-completed, non-archived workstreams |
+| **Blocking Decisions** | Pending decisions with status `open` or `escalated` — orange border if > 0 |
+| **Blocked Tasks** | Click to expand the list with blocking reasons |
+| **Events Today** | Progress events created on today's date |
+
+### What's next?
+
+System-derived action suggestions from `GET /state/next_steps`. Suggestions are
+generated when a decision is resolved or a workstream dependency is cleared, and
+they point to the first open task in the relevant workstream. These are derived
+on request and never persisted.
+
+### Blocking Decisions
+
+Inline resolution form for each pending decision. Expand a card, enter a
+rationale and "decided by" name, and click **Record & close**. The decision is
+resolved via `POST /decisions/{id}/resolve` and disappears from the list
+without a page reload.
+
+### Registered Projects
+
+Table of projects registered with `make register-project`, sourced from
+`milestone` progress events whose summary starts with
+`"Project registered with State Hub:"`.
+
+### Recent Activity
+
+Last 20 progress events across all domains, showing time, event type, author,
+and summary.
+
+---
+
+## Data source
+
+Polls `GET /state/summary` every **15 seconds**. Blocking decisions are fetched
+separately via `GET /decisions/?decision_type=pending` and only re-fetched
+after a successful resolve action — this prevents the inline form from being
+wiped on every poll.