Plugin: build private-alpha indexing and proposal control surface

[TristanEDU]

Goal

Turn the Obsidian plugin scaffold into the private-alpha vault control surface.

Scope

• Make indexing rules editable and understandable for non-developers.
• Add manual approval queues for rules_plus_approvals and manual_only.
• Show sync health, last sync time, indexed counts, denied counts, and redaction counts.
• Add write proposal review UI, but do not apply writes until the write safety gate is complete.
• Test only against fixtures and /Users/tjt/Documents/Tristan's Personal vault copy.

Done when

• The plugin can sync approved context to a local or hosted server.
• The plugin clearly shows what is indexed, denied, and waiting for review.
• Sensitive files require explicit user action before indexing.
• No live-vault write behavior is enabled by default.