fix(server): isolate blocker traversal budgets per root

Share queried graph facts across roots while retaining independent node/depth limits, expanded reachability and truncation for classification. Unrelated limited graphs must not change terminal subjects or delay archive deadlines. Prove depth/node overflow and overlapping-root liveness red/green, preserve the100-root SQL bound, and qualify existing owner assertions on isolated PostgreSQL.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

doc/plans/2026-10-30-attention-retention-sleep.md

@@ -25,7 +25,7 @@ The feed and worker share confirmation collapse, newer-run probes, issue visibil
 
 ## Existing mutation boundaries reactivate work
 
-Committed hints identify a company, source kind, and source ID where those values are known. Retention's own writes use exact source hints; blocker retention changes invalidate the company/source because multiple blocked roots can project one terminal subject. Reconstruction pages and due batches remain bounded. Review attention and interaction invokability are computed in company batches per candidate page; a full 100-candidate review page uses at most 20 statements and 100 confirmations use at most six. Decisions, recovery source links, runs, eligible agents, issue visibility, newer-run probes and blocker graphs also load in company batches per page. A 100-source decision or recovery page uses at most three statements; 100 failed runs use at most six; 100 blocker roots use at most 30 graph/source statements plus retention-state reads for their emitted entries. These evidence maps exist only for one load. Archive checks still lock and freshly re-read sources, terminal subjects and related eligibility. Ordinary execution, decision and budget mutations pass their affected company; exact decision sources are included.
+Committed hints identify a company, source kind, and source ID where those values are known. Retention's own writes use exact source hints; blocker retention changes invalidate the company/source because multiple blocked roots can project one terminal subject. Reconstruction pages and due batches remain bounded. Review attention and interaction invokability are computed in company batches per candidate page; a full 100-candidate review page uses at most 20 statements and 100 confirmations use at most six. Decisions, recovery source links, runs, eligible agents, issue visibility, newer-run probes and blocker graphs also load in company batches per page. A 100-source decision or recovery page uses at most three statements; 100 failed runs use at most six; 100 blocker roots use at most 30 graph/source statements plus retention-state reads for their emitted entries. These evidence maps exist only for one load. The blocker owner shares fetched node and edge facts while tracking depth, node count, expanded nodes and live-work reachability independently for each root. An unrelated graph reaching its limit cannot change a shallow root’s terminal subject or deadline. Archive checks still lock and freshly re-read sources, terminal subjects and related eligibility. Ordinary execution, decision and budget mutations pass their affected company; exact decision sources are included.
 
 Producer coverage includes decision creation and changes; interaction creation, resolution, expiry and supersession; issue creation, updates, blocker relations, checkout, adoption and release; agent hire, configuration, lifecycle, error clearing and deletion; budget incidents and company pause/resume; exhausted-run events and retry-run creation; native status, review, finalization and reconstruction; external conversation transitions; and imported blocker relations. Existing service transactions retain outer commit ownership. Savepoint release does not publish work before outer commit.