Preserve paged branch-local continuity semantics

[dajiaohuang]

Problem

Long campaigns exposed four authority-boundary defects: proposition-only actor-knowledge edits reset epistemic metadata and provenance; edits on a sibling branch retimestamped and reordered the current branch; fact/knowledge searches could not page beyond the first 100 results or provide cursor lookahead; and ContinuityService could neither traverse all three authority streams nor filter private facts before a player page was cut.

Solution

• preserve omitted actor-knowledge status, confidence, provenance, cause, and disclosure values while retaining explicit provenance clearing
• keep ContinuityCommit scene provenance bound to its newly committed event
• derive fact recency and updated_at from the selected branch revision head
• add validated offset pagination and a 1..500 internal page window to fact and actor-knowledge search
• page fact, event, and actor-knowledge continuity windows together with per-stream lookahead and next_offset metadata
• filter memory disclosure and context anchors before ranking and pagination
• document the direct-revision, scene-commit, branch, and cursor semantics

Verification

• 347 tests collected; full pytest suite passed with 2 expected skips
• focused 125-record fact/knowledge and 105-record three-stream continuity regressions passed
• player disclosure-before-pagination and sibling-branch recency regressions passed
• ruff check src tests
• git diff --check

Compatibility

Public facades can continue enforcing their existing <=100 response pages; the 500-record service boundary allows a one-record lookahead without unbounded reads. Continuity adds an optional offset and retrieval.pagination metadata without changing the default first-page result shape. Direct ActorKnowledgeService.revise now treats omitted optional fields as unchanged; source_event_id=None remains the explicit provenance-clear operation.