docs(admin): cut the cleanup docs down to something an admin will read

[MrAlders0n]

Follow-up to #8. This was pushed to that branch shortly before it was merged and missed the merge, same as the correction that missed #7.

#8's content fixes are live and correct — the 1× vs 3× pending thresholds and the "heard means an advert, not a wardrive" correction both landed. This PR is purely the length pass on top: −65 lines, no behaviour dropped.

Why

The section had grown into reference material for someone auditing the code rather than guidance for a region maintainer deciding what to click. A setting explained across six paragraphs reads as more dangerous and more complicated than it is.

What changed

• Three worked examples per setting down to one, and the "Worked example" labels dropped where the prose already reads as one
• Internal detail out of the body: status numbers (enabled = 3), the retired-points ledger's transaction semantics, "the detector is deliberately conservative", the map-parity subset argument
• Meta-commentary cut — "described individually below because they answer different questions", "the most important thing to understand"
• The "heard means an advert" callout from five paragraphs to three sentences. It's the most load-bearing point on the page and the length was burying it
• Same pass over Pending Repeater Links and Multi-region groups

Every correction from the earlier reviews survives: the 1× vs 3× pending thresholds, the retention clock running from last advert, sub-minimum values being rejected rather than clamped, and wardriving not resetting the lifecycle.

🤖 Generated with Claude Code

https://claude.ai/code/session_01KojjSrgSQQJW7Z8b3eakEA