Make trust score an absolute 0-100 scale instead of relative-to-max

[wwhitehead]

Problem

The displayed trust score divides combined_raw by the caller's maximum across all their contacts. That has three side effects:

• The top contact always shows 100, even if they have a single stale vouch.
• Every contact's score silently shifts whenever an unrelated contact gains or loses vouch weight.
• The same number means different things for different users, so scores aren't comparable.

Change

The score now maps combined_raw onto a fixed saturating scale:

score = 100 × (1 − 2^(−combined_raw / 4))

Each additional 4.0 of combined vouch weight closes half the remaining distance to 100 — the same halving convention as the existing 2-year time-decay half-life, applied to vouch mass instead of age. With the default 2/1/3 weights: two fresh direct vouches score 50, four score 75, and strong ties approach 100 asymptotically. A contact's score now depends only on vouches involving that contact, so it is stable and comparable.

• sql/contact-details-schema.sql — new c_score_half_raw constant + the scale, documented in the same style as the time-decay block. max_combined_raw is still returned for transparency but no longer feeds the score.
• js/contacts.js — the contact-list trust ring previously mirrored the relative normalization against the max of visible rows; it now uses the identical absolute formula (trustScoreFromRaw), so the list and the Contact Details ring always agree.
• js/contact-details.js — Trust Details dialog copy updated to describe the fixed scale.

To apply

Re-run sql/contact-details-schema.sql in the Supabase SQL editor — it only replaces the two functions; no schema changes.

Note on calibration

The half-point constant 4.0 is a calibration choice made against the default weights. If typical production combined_raw values run higher or lower, this is the knob to move — happy to adjust it against real data.

[wwhitehead]

BTW I really like where you're going with this. I saw a few other things as I was going thru the repo and the docs. I'll follow up when i have something a little more solid. This is going to be pretty cool.