Reorganize brain: projects/ top level, rename filenames, update homepage

- Moved everything from ideas/passepartout/ to projects/passepartout/
- Moved legal structures to projects/flags/
- Created missing _index.org files for all subdirectories
- Stripped redundant passepartout- prefix from filenames
- Rewrote root _index.org as generalized brain index (projects + concepts)
- Updated Hugo nav to Projects/Concepts
- Updated build script section descriptions
- Deleted stale ideas/passepartout-economics.md orphan

projects/passepartout/strategy/social-protocol-overview.org

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+:PROPERTIES:
+:CREATED:  [2026-05-24 Sun]
+:ID:       1d074690-a279-59cb-b91d-e9a22ae104ad
+:END:
+#+title: Passepartout Social Protocol — The Society (Decentralized Network)
+#+filetags: :passepartout:social-protocol:network:dids:
+
+Passepartout Social Protocol is the decentralized identity and communication layer that connects [[id:28c46769-c14b-42aa-ac7a-69d310157f8f][Passepartout]] instances:
+
+- **Self-sovereign identity** via HD key derivation (BIP-44)
+- **Encrypted messaging** via DIDComm (agent-to-agent and agent-to-human)
+- **Notes** as atomic, content-addressed, signed data units (mapped from Passepartout memory-objects)
+- **Relay Network** for censorship-resistant message routing
+- **Personal Data Store (PDS)** — the Merkle fact store exposed as a network-addressable service
+- **[[id:3c6b0449-a8fb-5b89-b82a-34efb21ef5b5][Compute marketplace]]** where instances offer symbolic engine capacity
+- **Contracts and liquid democracy** infrastructure
+
+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 the social protocol's CIDv1 content addressing.
+
+Revenue paths from the social protocol:
+- [[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
+- [[id:64708e1f-00e9-4cb7-b44b-ea0b98e5296d][Smart contracts + contract marketplace]] — the kill app
+
+See [[id:ed05cab4-88e9-4e25-b7c9-346fa39c69a0][Revenue streams overview]] for the full picture across all triad components.