Convert cross-references from [[id:uuid]] to [[file:name.org]]

All 117 inter-node links now use [[file:node-name.org][title]] format
which renders as clickable hyperlinks in both Emacs (C-c C-o) and
web-based org renderers (Gitea, GitHub). Each node retains its :ID:
UUID property for Emacs org-roam database features (backlinks,
capturing, node-find).

Prev format: [[id:uuid][title]] — Emacs only, dead text on web
New format:  [[file:name.org][title]] — works everywhere

ideas/passepartout-economics/agora.org

@@ -17,6 +17,6 @@ Agora is the decentralized identity and communication layer that connects Passep
 The PDS is Passepartout's in-process memory — the Merkle tree, the fact store, the memory-objects. Every memory-object already has a SHA-256 hash, which maps directly to Agora's CIDv1 content addressing.
 
 Revenue paths from Agora:
-- [[id:2e390c1d-65f3-5fb3-b898-ac3fc4291ee7][Premium username registry]] — $10M/yr at scale
-- [[id:1a2b38df-20ba-58ca-ba55-a072be67bd0d][PDS as a service]] — $18M/yr at scale
-- [[id:3c6b0449-a8fb-5b89-b82a-34efb21ef5b5][Compute marketplace]] — venture-scale
+- [[file:agora-usernames.org][Premium username registry]] — $10M/yr at scale
+- [[file:pds-as-a-service.org][PDS as a service]] — $18M/yr at scale
+- [[file:compute-marketplace.org][Compute marketplace]] — venture-scale