feat(trust): full Duniter web-of-trust membership (params + referents)

Slice 4 of Block 2. The pure rule was already parameterised; this adds the
policy, cold-start and UI around it.

- commons_core: WotParams (sigQty/stepMax/sigValidity, Duniter defaults) +
  WebOfTrust.membersWith; npubToHex helper (NIP-19 decode) for adding roots.
- WotSettings (keystore): the active parameters, configurable — a young
  network loosens them and tightens as it grows, as Ğ1 did. Defaults Duniter.
- TrustReferents: the bootstrap 'seeds' membership is measured from — a
  bundled asset (empty until real founders are curated, no invented keys)
  unioned with referents the user adds by npub/QR. Honest cold-start.
- TrustCubit: computes the full membership verdict against referents+params
  alongside the personal circle, and exposes a TrustTier (networkMember >
  inYourCircle > vouched > unknown). Certifications issued with the active
  validity (they expire and renew, Duniter rule).
- UI: chat trust badge by tier; a 'Network of trust' screen (manage roots +
  advanced params) reached from the profile. i18n en/es/pt/ast.

Tests: WotParams/membersWith, npubToHex, TrustReferents, WotSettings, and
TrustCubit tiers/membership. Resolves the WoT-parameters decision
(open-decisions §B). Trust net stays empty/undetermined until seeded — by
design; users bootstrap their own roots.

apps/app_seeds/lib/i18n/en.i18n.json

@@ -446,6 +446,28 @@
     "count": "Vouched for by {n}",
     "vouch": "I know this person",
     "vouched": "You vouch for them",
-    "circle": "In your circle"
+    "circle": "In your circle",
+    "member": "Trusted member of the network"
+  },
+  "wot": {
+    "title": "Network of trust",
+    "open": "Network of trust",
+    "help": "How trusted membership is decided: people vouch for each other, and trust spreads outward from a set of founding roots.",
+    "roots": "Trust roots",
+    "rootsHelp": "The founding identities the network is anchored to. Add people you trust (paste their identity code); membership is measured outward from them.",
+    "noRoots": "No trust roots yet — membership can't be worked out until the network is seeded.",
+    "addRoot": "Add a trust root",
+    "rootHint": "Paste an identity code (npub…)",
+    "add": "Add",
+    "rootAdded": "Trust root added",
+    "rootInvalid": "That's not a valid identity code",
+    "remove": "Remove",
+    "params": "Advanced parameters",
+    "paramsHelp": "Duniter rules. Loosen them for a young network; tighten as it grows.",
+    "sigQty": "Vouches to become a member",
+    "stepMax": "Max distance from a root",
+    "validityDays": "Vouch validity (days)",
+    "reset": "Reset to Duniter defaults",
+    "saved": "Saved"
   }
 }