feat: live multiuser data propagation (#11)

[DDecoene]

Closes #11.

When one session mutates a table, every other session currently BROWSE-ing that same table refreshes automatically — no manual re-query. Type in one browser window, watch another repaint.

How it works

• Prereq fix: ServerDatabaseBridge.closeDatabase() is now detach-only — it no longer closes the SQLite handle shared across sessions (one user closing a DB previously broke everyone else's queries).
• Mutation signal: exec() fires an onMutate hook → Session marks itself dirty → after the message it calls a notifyChange callback injected by SessionManager. Every write path (REPLACE/APPEND/DELETE/PACK/grid edits) routes through exec(), so no per-command bookkeeping.
• Fan-out: SessionManager.broadcast(db, table, except) sends a new data-changed message only to sessions whose current view matches (server-side relevance filter), debounced per table so a burst coalesces into one refresh.
• Client: Terminal handles data-changed and, if a Grid is open on that table, triggers the existing F5 refresh path (repaints in place, preserves selection).

Tests

• Unit: bridge onMutate + shared-handle regression; SessionManager broadcast filters by view, skips originator, coalesces a burst.
• E2E (tests/propagation.spec.ts): two browser contexts both BROWSE the same table; edit in one, assert the other repaints with no re-query. Passes live.
• Full suite: 206 tests green; tsc --noEmit clean.

Ships as v0.9.0. Design/plan under docs/superpowers/.

[DDecoene]

Update (GitFlow): re-based onto release/v1.1.0 and versioned as v1.1.0 (this is milestone v1.1.0 — beyond parity work, not a 0.x parity-track release). Per the new GitFlow policy, this PR merges into release/v1.1.0, not main; the v1.1.0 tag is cut only when that release branch merges to main. 206 tests green.