[VERIFY-01] Remediate all exact-main audit findings #96

TASKS IDs: UI-GATE, LIVE-01, SEC-REVIEW, STABILITY, DEMO-REHEARSAL evidence
PRD: 0.3-0.4, 6.1, 11-17
Related issues: #45, #65, #89

This issue owns remediation of every concrete defect reproduced during the 2026-08-31 exact-main audit.

Product and security scope:

• bound durable event, run, message, and Shepherd collections so reaching the schema limit cannot make state permanently unwritable
• reject hostile Origin and Host mutation requests in tokenless loopback mode without breaking the local demo
• resolve the non-loopback tokenless Compose posture carried by [SEC-REVIEW-2] Independent trust-boundary review and the carried compose exposure #89
• keep Volcengine credentials out of Terraform state and cloud-init user data
• remove the Project Group mention caret race
• give every Settings numeric input an unambiguous accessible name
• remove the 1280x800 Create Agent fractional clipping

Verification and harness scope:

• make all 38 committed Playwright tests green at 1280x800 and 1440x900 without weakening assertions
• make the legacy live starter gate honor the Shepherd-route default and resolve codex through PATH safely
• confine the live model-review gate to one current-tree test and one external request
• make the sparse live-runtime gate volume-aware on the affected macOS container host while preserving sandbox, cleanup, and credential boundaries
• add an enforced repository coverage gate with an 80 percent minimum
• run pinned Terraform fmt and validate for deploy/volcengine

Documentation scope:

• reconcile TASKS, SHEPHERD, LOCAL_POC, FIXES, BUILD_LOG, and SHEPHERD_TEST_REPORT with exact observed evidence
• record [UI-GATE] Complete the final six-surface accessibility and visual gate #45, [LIVE-01] Run the exact-head sparse live Shepherd Mission and legacy Agent continuity gate #65, and reopened [SEC-REVIEW-2] Independent trust-boundary review and the carried compose exposure #89 ownership and remaining independent gates truthfully
• do not self-claim independent UI or security review

Primary files: database schema and bounded append paths; server auth/config and tests; Compose and Volcengine deployment; Project Group, Settings, Create Agent UI and Playwright tests; live runtime/model-review harness; package and Vitest coverage configuration; project evidence documentation.

Acceptance:

• every new behavior is introduced by a causal failing test and verified green
• complete Playwright matrix passes at both required viewports
• live gates are bounded, current-tree-only, redacted, and pass on this host when code can make them portable
• repository coverage command enforces at least 80 percent
• Terraform format and validation pass with a pinned version
• npm audit and npm run check pass
• documentation contains no known stale status for this audit scope
• branch starts at current origin/main and is delivered through a linked PR.