hermes - 💡(How to fix) Fix time_reconciler: add LLM proposal schema and approval report renderer

Parent: #29631

Goal

Implement the proposal/approval report layer for time_reconciler using a strict schema and privacy-safe rendering.

Scope

• Create a strict JSON schema or equivalent validation structure for LLM-produced mapping proposals.
• Add a prompt/template that instructs the LLM to cite evidence and counterevidence and never request execution.
• Render approval reports in Markdown/Slack-friendly text grouped by:
  • safe/high-confidence
  • needs confirmation
  • personal/non-billable
  • reject/leave alone
• Add privacy options:
  • redact raw titles/domains in report output
  • avoid persisting raw activity by default

Acceptance Criteria

• Proposal schema rejects malformed LLM output.
• Approval report renders from synthetic proposal fixtures.
• Redaction option removes or masks sensitive titles/domains.
• No API writes are possible from this layer.
• Tests use synthetic data only.