fix(install): preserve user fleet data on re-seed + refresh active units (#631)

CRITICAL data-loss in the routine update path. `mosaic update` auto-runs
install.sh keep-mode sync (#610); the rsync --delete honored PRESERVE_PATHS but
fleet/ was not listed, so the sync WIPED ~/.config/mosaic/fleet/roster.yaml (and
fleet/run, fleet/agents). Any user running `mosaic update` lost their fleet.

PRIMARY (data-loss):
- install.sh PRESERVE_PATHS += fleet/*.yaml, fleet/agents, fleet/run. The
  framework still SEEDS fleet/examples + fleet/roles + fleet/roster.schema.json
  (synced); the operator's roster, custom rosters, per-agent env, and heartbeat
  run dir are preserved.
- Made the cp (no-rsync) fallback GLOB-AWARE so fleet/*.yaml is preserved there
  too; fixed the restore to re-glob per pattern (restores only the user file,
  not the freshly-synced fleet/ dir).
- file-adapter.ts (TS installer): mirrored the preserve list for dual-installer
  parity. (syncDirectory is copy-only — never --delete — so it never had the
  bug; this is parity + belt-and-suspenders.)

SECONDARY (stale active units):
- refreshActiveFleetUnits(): the re-seed updates ~/.config/mosaic/systemd/user
  but systemd runs ~/.config/systemd/user, so shipped unit fixes (#627) did not
  take effect after update. `mosaic update` now copies the fresh mosaic-*.service
  → the active dir + daemon-reload (best-effort, only when a fleet is installed).

Verified: bash F6 fixture (roster/custom-yaml/agents/run survive + examples
refreshed + schema seeded), 20/20 migration matrix; TS file-adapter keep-mode
test; 2 refreshActiveFleetUnits unit tests. tsc/eslint/prettier/sanitize clean.

Refs #631

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EsgTQzV5YUGk1JtCLP4B83

docs/TASKS.md

@@ -82,3 +82,7 @@ Active workstream is **W1 — Federation v1**. Workers should:
 ## north-star doctrine consolidation — doc PR — feat/north-star-doctrine
 
 - Status: applied Mos's consolidated merge-map to docs/fleet/north-star.md (budget governance + control plane/central register + 200k cap + delegation + unified-identity Fleet + role-based naming + tmux security + drift re-captures). Doctrine only; #622/#623/#625/#628 out-of-scope. Conflict checklist green. Detail: scratchpads/north-star-doctrine.md.
+
+## #631 — re-seed preserves user fleet data (CRITICAL) — fix/631-reseed-preserves-fleet-data
+
+- Status: implemented + tested. PRIMARY: install.sh PRESERVE_PATHS += fleet/\*.yaml + fleet/agents + fleet/run (glob-aware cp-fallback); TS parity. SECONDARY: refreshActiveFleetUnits propagates unit fixes to ~/.config/systemd/user on mosaic update. bash F6 + TS + unit tests green. Detail: scratchpads/631-reseed-preserves-fleet.md.