docs(dedupe): one owner for the finish rule, and the Gitea index routes instead of restating

Two independent copies of the same law, and each page cited its own numbers. The finish rule —
stop when independent sources agree, when the retrieval budget is spent, or when every claim is
met; report gaps, never invent a source — stood in full in `agentic-search-best-practices.md`
(with the loop caps: 20 steps, re-plan every 4) and again in `research-effectiveness.md` without
them. The operational page owns it; the measurement page keeps the pointer and the one thing
that is its business, which is that unbounded loops are why "infinite re-search" is a named
failure mode.

`tools/gitea/index.md` was a second copy of its own directory: an architecture table, a
management command table, a data-persistence path table and a boot-persistence paragraph, every
one of them a subset of `architecture.md`, `management.md` and `data-persistence.md` — verified
line by line before cutting, including the two facts that looked unique to the index (the
`dns_enabled: false` default network, the `/opt/gitea` leftover) and turn out to be owned
upstream with more detail. The index now answers "which page owns my question" and gives three
one-line orientation facts. Gitea's live version was re-read while I was in there: still 1.27.3.

Refs #64

omp-docs/agentic-web-research/research-effectiveness.md

@@ -96,13 +96,11 @@ Pi already runs a similar model with its parallel `researcher` and `scout` subag
 
 ## The Finish Rule
 
-Research must end. Stop when any one is true:
-
-1. Two or more independent sources agree on the answer.
-2. The retrieval budget is spent.
-3. The required confidence is met for every claim.
-
-Report gaps honestly. Do not invent a source to fill one.
+The rule itself — stop when independent sources agree, when the retrieval budget is spent, or
+when every claim has the required confidence, and report the gaps instead of inventing a source —
+is owned by [Agentic Search Best Practices](agentic-search-best-practices.md#the-finish-rule),
+the page an agent reads before it starts a loop. What belongs here is the measurement: unbounded
+loops are why "infinite re-search" is a named failure mode in the next section.
 
 ## Failure Modes and Guardrails