Both API and crawler now open the database read-write, so the
ModeReadOnly branch was dead code. Collapse to a single New(path)
entry point. The API previously inherited the write-mode pool size
of 1, which would have serialized its reads; restore a 10-connection
pool for all callers. Writes are still serialized by writeMu and
SQLite's own locks, so extra connections do not cause contention.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

A vouch is a weaker signal than an actual follow: the user is asserting
non-spam without committing to see the target's posts. Carry a per-edge
weight through the graph so vouch-only edges contribute proportionally
less flow than a full follow.

Config: vouch.weight (default 0.5, range (0, 1]).

PageRank and TrustRank inner loops now divide by outWeight (sum of
outgoing edge weights) instead of outDegree (count). Each in-edge
carries its own weight; a source's score flows to each target in
proportion to weight / outWeight. Follow and vouch edges share the
same adjacency list — only their weights differ. outDegree is still
tracked as an int so the pubkeys table's Following column remains a
count. New test verifies that lowering the weight produces a lower
score for a vouch-only recipient.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Having both fields required the user to keep them consistent: enabling
with weight=0 (or disabling with weight=0.5) both produced inconsistent
states. Use weight alone — 0 means off (endpoints return 404 and the
ranking calculator skips streaming vouches entirely), > 0 means on and
is the edge weight. Default 0 preserves prior off-by-default behaviour.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Vouches and reports are now plain signed Nostr events rather than a
NIP-98-wrapped private API, so the data is publishable to any relay and
shared with the wider network. A new internal/ingest package backs both
ingestion paths:

- Crawler (pull): alongside kind:3/0, fetches each author's kind:1984
  reports and kind:10040 vouch sets. Replaceable kinds (3/0/10040) share
  one small-limit query; kind:1984 (append-only) gets its own query
  capped at the newest 50 so it can't crowd out the replaceable events.
- POST /event (push): accepts a single signed event for immediate
  ingestion, keeping the anti-inflation rule (untrusted authors dropped).

Both paths verify signatures before storing. The old /vouch and /report
endpoints and the NIP-98 middleware are retired.

Reports are kind:1984 profile-level (p tag, no e tag) spam/impersonation
events. Vouches are membership in a custom replaceable kind:10040 set and
follow the same lifecycle as follow edges: refreshed via last_seen, never
actively deleted, aged out by the ranking staleness window. Vouch-beats-
report precedence is resolved at ranking time (GetTrustWeightedReports
excludes a reporter who also vouches for the same target).

A source that both vouches for and reports the same target no longer gets
special handling. The vouch adds flow and the report subtracts it at
ranking time, which roughly cancels out on its own — so the extra
NOT EXISTS subquery in GetTrustWeightedReports was redundant complexity.

Vouches now live in a standard NIP-51 follow set (kind:30000) tagged
d=vouch, instead of a custom kind:10040. Other clients can render it as a
people list, and the generic identifier (no project prefix) leaves room
for a shared convention. Other follow sets are ignored.

Because kind:30000 is addressable by d, it can't share the no-d query
with kind:3/0; it gets its own #d-filtered fetch (fetchVouchSetsFromRelay),
and ingest gates it via IsVouchSet.

A REQ carries multiple filters (OR'd), so the kind:3/0 filter and the
kind:30000 vouch-set filter (constrained by #d, scoped to its own filter)
now ride in a single SubManyEose call per relay — one connection, one
round-trip — instead of two separate fetches. kind:1984 reports stay in
their own subscription to keep their per-query limit clean.

- ingest: drop hand-written dTagValue, use go-nostr's Tags.GetD()
- ranking: compute report-penalty F only for reported targets instead of
  scanning the whole graph (drops an O(numNodes) alloc + full edge scan)
- repository/models: remove unused ReportAggregate.NumReporters field and
  its COUNT(*) (only TotalReporterTrust is consumed)