Expose and document File-content matching

[frap129]

Parent

#38

What to build

Make fileContains visible and understandable in the existing sidebar and project guidance so Rule authors can configure it and reason about File observations, trust boundaries, lifetimes, and earliest dispatch.

Acceptance criteria

• The sidebar condition summary and existing detail surface render scalar and multi-literal fileContains declarations clearly.
• Sidebar rendering tests cover content conditions without introducing a new UI or diagnostics surface.
• Rule-author guidance documents syntax, normalization, literal semantics, same-observation correlation, condition-family algebra, supported observation sources, and excluded sources.
• Architecture and lifecycle guidance describes initial, mid-session Durable, and Transient delivery at the earliest applicable dispatch, including persistence and recovery behavior.
• The domain glossary consistently uses File observation, Working context, Matched rule, Durable delivery, Transient delivery, and earliest dispatch terminology.
• Project structure documentation includes every production module added or removed by the parent work, and stale descriptions of legacy file matching are removed.
• The crafting-rules guidance is updated consistently with the public Rule contract.

Blocked by

• Make File observations the sole file-matching source #58
• Harden mid-session Rule delivery and recovery #60