Fix three fresh-install bugs: missing yaml dep, TELOS.md drift, dead Assistant tab

[BearGare]

Three independent fixes found during a fresh v6.0.0 install. Each is its own commit and can be reviewed/reverted independently.

1. Missing yaml dependency for deployed hooks/TOOLS scripts

Several deployed scripts (hooks/lib/identity.ts, LIFEOS/TOOLS/Banner.ts, LoadSkillConfig.ts, PipelineOrchestrator.ts, and others) import the yaml npm package, but the deploy pipeline never declares or installs it: there is no root package.json anywhere in the release tree, and neither InstallEngine.ts nor DeployCore.ts runs bun install. First run after a fresh install throws Cannot find package 'yaml'.

Fix: add install/package.json (with yaml pinned to the version already used by the Agents/Prompting skill tools) and a new DeployCore.ts step that copies it to <configRoot>/package.json and runs bun install --cwd <configRoot>, so yaml resolves via node_modules for both <configRoot>/hooks/ and <configRoot>/LIFEOS/. Applied to both the top-level and the skills/LifeOS-vendored copy of DeployCore.ts (the repo carries the two byte-identical). Verified with dry-run and --apply against a scratch config root, and by importing yaml from a deployed hooks/lib/*.ts location.

2. TELOS.md vs legacy split-file drift

TELOS.md's own banner says "this is the single source of truth... Pulse reads this file", and GenerateTelosSummary.ts's LEGACY_FILE_TO_SECTION comment says the unified TELOS.md superseded the split files on 2026-05-01. But the shipped fresh-install template still carries both representations un-migrated, and the generator prefers the legacy per-topic file whenever it still exists on disk. Net effect: a fresh install silently ignores edits to TELOS.md in favor of the legacy files' stale samples, contradicting what TELOS.md tells the user.

Two other consumers read the legacy files with no TELOS.md fallback at all: PULSE/checks/life-morning-brief.ts and skills/Daemon/Tools/DaemonAggregator.ts. Archiving the legacy files without fixing these would have made them permanently blind to TELOS.md-only content.

Fix: archive the 8 legacy files to USER/TELOS/Archive/2026-05-01/ (the fully-migrated state the generator already expects); rewrite TELOS/README.md to document TELOS.md as the single file to edit; add a TELOS.md-section fallback to both life-morning-brief.ts and DaemonAggregator.ts. Verified end-to-end against a scratch config root for the generator and both consumers.

3. Assistant module stub so the Pulse Assistant tab degrades honestly

pulse.ts:127 dynamically imports ./Assistant/module whenever config.da.enabled is true, and wires its exports to every /assistant/* route backing the fully-built Assistant tab (Observability/src/app/assistant/page.tsx). That module never existed in the repo — the import throws, is caught, logs "Assistant module not available", and the entire tab API silently no-ops.

A full backend (identity/personality/diary persistence, cron CRUD) is a separate feature, tracked in #1419 (which also documents a /da/* vs /assistant/* naming drift between the design doc and the shipped frontend). This PR only adds a stub so the current no-op is deliberate rather than an accident of a caught import error: GET /assistant/health returns identity_loaded: false (making the frontend's existing EmptyStateGuide/isFreshInstall path deterministic), read endpoints return correctly-typed empty JSON, and mutating requests return 501 with a clear message instead of silently doing nothing when a user clicks Save/Delete. Verified via a standalone harness exercising every route.

Relates to #1419.