Implement TREV-WP-0002 Stage 0 foundation: schemas, pure fold, golden Phase

Delivers the offline runnable specification foundation for the Trust Layer
(TSD §3-§6), not a hosted Trust Service:

- JSON Schemas for Phase Manifest, Ledger Entry, Extension Contract, and
  Conversion Attestation, encoding the Stage 0 working defaults (Q3 future
  license enum, Q6 single-currency Phases, Q8 required longstop_at).
- src/target_revenue: pure Outstanding Target fold, SHA-256 hash-chain
  verification, Ed25519 signing helpers, extension conformance checks
  (including a core-term-redefinition heuristic), and conversion detection
  that never requires an attestation document to determine conversion status.
- examples/phase-001: golden Phase package matching the concept doc's
  worked example, generated via scripts/generate_golden_phase.py so the
  hash chain is computed by the library itself, not hand-typed.
- 32 passing pytest tests covering manifest/ledger/extension conformance,
  tamper/reorder detection, and the full lifecycle fold to conversion.
- docs/adr/ADR-0001: proposed (not accepted) Stage 0 stack choice, per the
  WP-0002-T01 human-accept gate — implementation proceeded against the
  proposal as the workplan note permits, but the task stays open.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

schemas/phase_manifest.schema.json

@@ -0,0 +1,108 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$id": "https://target-revenue.example/schemas/phase_manifest.schema.json",
+  "title": "Phase Manifest",
+  "description": "Stage 0 schema per specs/TechnicalSpecificationDocument.md §3.1 and specs/OpenQuestions-WorkingDefaults.md Q3/Q6/Q8. Field names and semantics are authoritative from spec/TargetRevenueLicenseConcept.md §16.",
+  "type": "object",
+  "required": ["framework", "license", "phase"],
+  "additionalProperties": false,
+  "properties": {
+    "framework": {
+      "type": "string",
+      "description": "Framework version tag, e.g. TRF-0.1."
+    },
+    "license": {
+      "type": "string",
+      "description": "TRSL version tag, e.g. TRSL-0.1."
+    },
+    "phase": {
+      "type": "object",
+      "required": [
+        "id",
+        "milestone_release",
+        "initial_target",
+        "future_license",
+        "degeneration_policy",
+        "longstop_at",
+        "ledger"
+      ],
+      "additionalProperties": false,
+      "properties": {
+        "id": {
+          "type": "string",
+          "pattern": "^trsl:phase:[a-zA-Z0-9._-]+$",
+          "description": "Globally unique, immutable once published."
+        },
+        "milestone_release": {
+          "type": "object",
+          "required": ["name", "source_revision"],
+          "additionalProperties": false,
+          "properties": {
+            "name": { "type": "string" },
+            "source_revision": { "type": "string" },
+            "artifact_sha256": {
+              "type": "string",
+              "pattern": "^[a-f0-9]{64}$",
+              "description": "Recommended; required if a built artifact (not just source) is governed."
+            }
+          }
+        },
+        "initial_target": {
+          "type": "object",
+          "required": ["amount", "currency"],
+          "additionalProperties": false,
+          "properties": {
+            "amount": { "type": "number", "exclusiveMinimum": 0 },
+            "currency": {
+              "type": "string",
+              "pattern": "^[A-Z]{3}$",
+              "description": "ISO 4217 code. Working default Q6: one native currency per Phase."
+            }
+          }
+        },
+        "target_basis": {
+          "type": "object",
+          "description": "Recommended transparency metadata (working default Q5), not legally required.",
+          "additionalProperties": false,
+          "properties": {
+            "estimated_effort_days": { "type": "number", "minimum": 0 },
+            "daily_rate": { "type": "number", "minimum": 0 },
+            "approved_direct_costs": { "type": "number", "minimum": 0 },
+            "target_multiple": {
+              "type": "number",
+              "minimum": 0,
+              "description": "Open decimal per working default Q4. Guidance classes {0,1,10,100,1000} are not a closed enum."
+            }
+          }
+        },
+        "future_license": {
+          "type": "string",
+          "enum": ["MIT", "Apache-2.0"],
+          "description": "Working default Q3: closed enum for Stage 0."
+        },
+        "degeneration_policy": {
+          "type": "string",
+          "pattern": "^trsl:policy:[a-zA-Z0-9._-]+@[0-9]+(\\.[0-9]+)*$",
+          "description": "e.g. trsl:policy:linear-longstop-v0@1.0 (working default Q7)."
+        },
+        "longstop_at": {
+          "type": "string",
+          "format": "date-time",
+          "description": "Required for Stage 0 per working default Q8. Full-remission / maximum-protection instant."
+        },
+        "ledger": {
+          "type": "string",
+          "description": "URL or relative path URI to the authoritative Target Ledger for this Phase."
+        }
+      }
+    },
+    "extensions": {
+      "type": "array",
+      "items": {
+        "type": "string",
+        "pattern": "^trsl:extension:[a-zA-Z0-9._-]+@[0-9]+(\\.[0-9]+)*$"
+      },
+      "description": "Optional. Applicable monetization profiles/extensions for this Phase."
+    }
+  }
+}