feat: add Publication history across CLI, MCP and desktop

[nokhodian]

Summary

Agents and workflows could publish content without a unified local history. Add a profile-scoped Publication section that records successful posts, comments, replies, articles, videos and shared-channel publications, with their exact content, returned identities and workflow/agent source.

• CLI first: publication list|get|register|stats, offline reference, and a publication.register node for custom publishers.
• Automatic registration at publishing success boundaries, including partial success and retries; tracking failures warn without retrying a remote publication. Private messages, drafts and failed results are excluded.
• Read-only MCP/assistant history tools, registration behind existing mutation controls, and desktop filters, pagination, details, links and execution navigation.
• Migration 062 is additive. History starts with installation; external publishers register after success rather than being observed automatically.

Type of change

• New feature (non-breaking change that adds functionality)

Validation

• go build ./... and go build -tags nosocial ./...
• Full Go suite: go test -p 2 ./... (5,876 tests)
• Targeted nosocial tests: publication, registration node, node registry, MCP and org grants
• Full frontend suite: 154 files / 1,646 tests (npm test -- --maxWorkers=2)
• Frontend production build and Wails Publication bridge tests
• Changed Go files formatted; diff whitespace checks clean
• Unreleased changelog, offline reference and agent guidance updated
• Tests use fake publishers; no live account publication occurred

Notes for reviewers

Records remain profile-scoped; metadata capture excludes credentials and private destinations. MCP registration retains the existing mutation gate and org grant mode is unchanged. Registration does not send content. Discord channel metadata is used to distinguish shared channels from private messages.

Prepared against current master in an isolated worktree. Existing workspace dependency/generated-file changes and the separate coder workflow-guidance commit are excluded. The coder publication prompt pins the turn's CLI, profile and custom database. Host-dependent test fixtures were corrected without changing runtime discovery behavior; broad checks use reduced concurrency after an initial timing failure in the existing cancellation test.