feat: directional sync + devcontainer demo + graph polish/persistence

[aniongithub]

A self-documenting devcontainer + the graph polish from last night. Three commits.

1. 9a80027 — Graph polish: translucent edges, opaque arrows, fit-all button

• Edges are translucent so they don't visually merge with nodes of the same color: path edges at 0.5 alpha, reference edges at 0.55. Path edge width bumped 1px → 1.5px to compensate for softer contrast.
• Arrowheads stay opaque via linkDirectionalArrowColor set to the full-alpha edge color — the arrow reliably covers the translucent line where it would otherwise show through.
• Arrow length 4 → 2.5 (was oversized at the new node radius).
• New "fit all" button in the graph toolbar — forceGraph.zoomToFit(400ms, 40px). Handy when a search filter has narrowed the visible set to a few far-apart nodes.
• withAlpha() helper handles #rgb, #rrggbb, #rrggbbaa, and rgb()/rgba() so the alpha override survives whatever format CSS vars use.

2. 7c9a757 — Directional sync + devcontainer demo via the wiki itself

The headline feature: a fresh git clone + devcontainer rebuild now downloads mind-map's own documentation from the project's GitHub wiki via the very sync feature we're demonstrating.

Sync direction (new code)

• New SyncMapping.Direction field. Values: bidirectional (default, backward-compatible), pull (read-only — never push local changes), push (write-only — never pull remote changes).
• SyncDirection.Normalize() coerces empty/unknown values to bidirectional so existing configs keep working.
• syncTarget honors direction: pull skips copyFromWiki + commit + push; push skips copyToWiki + reindex. Both modes still fetch+merge so push has a base and pull picks up remote changes — only the local copy directions are gated.
• Regression tests: TestPullOnlyDoesNotPushLocalChanges and TestPushOnlyDoesNotPullRemoteChanges.

Devcontainer wiring

• .devcontainer/devcontainer.json bind-mounts ${localWorkspaceFolder}/.mind-map as the vscode user's ~/.mind-map/ so the committed sync config is what mind-map serve reads.
• .mind-map/config.json declares a single pull-only mapping at prefix:"" pointing at https://github.com/aniongithub/mind-map.wiki.git.
• .mind-map/.gitignore keeps everything but config.json out of git (wiki content, SQLite index, shadow clones, logs all regenerated on first launch).
• .vscode/launch.json drops --dir overrides — defaults route to ~/.mind-map/wiki where sync lands content.

SKILL.md updates

• Adds move_page to the tools list + a dedicated section explaining why agents should use it instead of create+delete (atomic rename, preserves the link graph).
• Adds a "Wiki Layout (Recommended)" section nudging agents toward <project-or-area>/<category>/<page>. Not enforced — encouraged so prefix-based sync mappings have meaningful shapes.
• Adds a "Sync" section explaining the new direction modes.

testdata removal

The previous testdata/ contents have been pushed to the GitHub wiki (33 pages: concepts/, architecture/, agents/, design/, comparisons/, guides/). Fresh devcontainer launches pull that content down via sync instead of carrying it in-repo.

Verified end-to-end

Rebuilt the devcontainer, ran mind-map serve, sync created the shadow clone and populated 34 pages into the wiki dir within 1.5 seconds. /api/context returned the full page list. Pull-only direction confirmed in logs (no commit/push attempted).

3. acfb1f7 — Graph auto-fits on first load, persists pan/zoom

• On first mount we subscribe to onEngineStop and call zoomToFit(400, 40) the first time the simulation cools, so users always land on the full graph rather than a random pre-layout fragment.
• onZoomEnd persists the current {k, x, y} transform to localStorage under mm-graph-view. Subsequent loads restore it via centerAt + zoom (duration=0) and skip the auto-fit.
• Guarded with a closure-local flag so zoom-end events during the auto-fit animation don't clobber the meaningful saved state, and so later simulation kicks (e.g. theme changes re-feeding data) don't snap the view back.