chore(m5): add Spool Daemon upgrade notice + clean up docs

[graydawnc]

Summary

Continuation of #112 / #113 / #114 / #115 / #116. Adds the one-time upgrade notice for users coming from a pre-M5 Spool, and finishes the cross-cutting documentation cleanup that earlier PRs deferred.

-1466 / +184 net.

Upgrade notice

A React modal (not a native dialog) so it matches Spool's design system — warm card, Geist Sans, accent CTA — and uses the real Spool Daemon app icon (copied from spool-lab/spool-daemon).

Trigger logic (computed in main, exposed via IPC):

shouldShow = !spoolDaemonNoticeShown && !wasNewDb() && initialUserVersion < 5

Scenario	wasNewDb	initialUserVersion	Shows?
Brand-new user installs post-M5 build	true	0 (gated by wasNewDb)	❌
Existing user upgrades from v4	false	4	✅
Existing user upgrades from v0–v3 (very stale)	false	< 5	✅
Already-upgraded user, second launch	false	5	❌
User quits without dismissing	—	—	❌ next launch (initialVersion is now 5)

The "lost on quit-before-dismiss" behaviour is intentional — this is an informational nudge, not critical state, and avoiding a second persistent flag keeps the design simple. (VS Code-style "what's new" notices behave the same way.)

wasNewDb() and getInitialUserVersion() are added to @spool-lab/core's db.ts. Both are captured before runMigrations() runs so the post-migration state doesn't muddy the detection.

Dialog UX:

• Daemon icon, 72×72 squircle
• Title "Connectors moved to Spool Daemon"
• Body explains that connectors live in Spool Daemon now and synced data was removed
• Primary "Get Spool Daemon" → shell.openExternal('https://spool.pro/daemon') and persists shown flag
• Secondary "Maybe later" → just persists shown flag
• Backdrop click / Escape do not dismiss (forces an explicit choice — but both choices are non-blocking)

Side fix: uiPreferences now respects SPOOL_DATA_DIR (was hardcoded to ~/.spool/ui.json regardless of env override). Surfaced during sandbox smoke testing and would have leaked dialog-shown state out of test sandboxes.

Doc cleanup (cross-cutting)

• README.md — drop stars/bookmarks/likes from tagline, drop the Connectors bullet, replace with a forward to Spool Daemon, drop the fieldtheory-cli acknowledgement (Twitter bookmarks gone)
• DESIGN.md — drop bookmarks/capture from Product Context, rewrite Source Chips + Sources Panel sections to be session-only, drop "Capture / add" icon, fix Status Bar dot color guidance
• docs/spool-positioning.md — strip bookmark/star marketing, end with a forward to Spool Daemon
• packages/core/README.md — drop "connected sources" / "connector sync engine" / "connector loader" / "connector registry"; replaced with watcher + stars
• Deleted docs/connector-developer-guide.md (607 lines) and docs/connector-sync-architecture.md (924 lines) — both exclusively about the removed subsystem

docs/superpowers/* historical plans + specs left intact (they're dated git-log-style records, not current docs).

Features that should still work post-PR (verified)

Feature	Verification
Core build + tests	48/48 pass (migration-v5 tests now also cover wasNewDb / getInitialUserVersion)
CLI build + tests	21/21 pass
App typecheck	pnpm exec tsc --noEmit clean
App electron build	pnpm build:electron clean
pnpm install --frozen-lockfile	Clean
Upgrade-path smoke	Downgraded sandbox to user_version=4, cleared spoolDaemonNoticeShown, launched dev → modal appears with daemon icon, copy correct, "Spool Daemon" doesn't break across lines
Fresh-install smoke (logic)	wasNewDb=true short-circuits; covered by migration-v5.test.ts "no-op fresh install" case
Re-launch after dismiss	Flag persists in ui.json, getDaemonNoticePending returns false, modal does not reappear
Get Spool Daemon button	Opens https://spool.pro/daemon via shell.openExternal (not spool.dev — that's not the canonical domain)
Session search / star / settings	Untouched, still functional

Test plan

• Core 48/48 pass with new accessor coverage
• CLI 21/21 pass (rebuilt better-sqlite3 for node ABI before running)
• App typecheck + build clean
• pnpm install --frozen-lockfile clean
• Manual smoke: upgrade-path modal looks right, button actions persist flag, re-launch doesn't re-trigger
• All spool.dev/daemon references swept to spool.pro/daemon

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