feat: add extraction schema, sidebar nav, few-shot prompting, and prompt settings

Overhaul extraction pipeline with new TradeItem model, conversation flow,
and dedicated extraction endpoint. Add sidebar navigation with NavMenu
component and landing page. Introduce few-shot prompting service and
tests. Add prompt settings and email upload specs. Update OpenSpec
tooling with improved export-spec and extract-feature commands. Archive
completed changes and export full specs.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

openspec/changes/archive/2026-04-06-update-extraction-schema/specs/extraction-schema/spec.md

@@ -0,0 +1,63 @@
+## ADDED Requirements
+
+### Requirement: TradeItem schema
+
+The system SHALL define a `TradeItem` class with the following fields representing a single trade leg extracted from a sales email:
+- `valuedate` (string, dd/MM/yyyy format)
+- `counterparty` (string, full legal name as it appears in the email)
+- `legal_entity` (string, nullable — populated after counterparty disambiguation via lookup tool)
+- `trade_id` (long, Murex trade identifier)
+- `display_ccy` (string, ISO currency code e.g. "GBP", "USD")
+- `pv` (double, present value)
+- `breakclause` (string, "Y" or "N")
+
+JSON serialization SHALL use snake_case property names via `[JsonPropertyName]` attributes.
+
+#### Scenario: All fields populated
+
+- **WHEN** the extraction agent produces a TradeItem with all fields
+- **THEN** the JSON output contains all seven fields with snake_case keys and correct types
+
+#### Scenario: Legal entity null before disambiguation
+
+- **WHEN** the extraction agent produces a TradeItem before counterparty lookup
+- **THEN** the `legal_entity` field is null and all other fields are populated
+
+### Requirement: ExtractionResult wrapper
+
+The system SHALL define an `ExtractionResult` class containing a `List<TradeItem> Items` property. All extraction output from a single email SHALL be wrapped in this object.
+
+#### Scenario: Single email with multiple trade legs
+
+- **WHEN** an email contains two swaps with two legs each (4 trades total)
+- **THEN** the ExtractionResult contains an `items` array with 4 TradeItem objects
+
+#### Scenario: JSON output structure
+
+- **WHEN** the ExtractionResult is serialized to JSON
+- **THEN** the output has the shape `{"items": [{"valuedate": "...", ...}, ...]}`
+
+### Requirement: Extraction mapping rules
+
+The extraction agent SHALL follow these mapping rules when converting email content to TradeItems:
+- Each swap leg (identified by a unique Murex trade ID) becomes a separate TradeItem
+- The `valuedate` SHALL be parsed from date references in the email (e.g., "OB 27/11/2025") and formatted as dd/MM/yyyy
+- The `counterparty` SHALL be the full legal entity name as stated in the email prose
+- The `display_ccy` SHALL be derived from the currency symbol or code in the email (e.g., "£" or "PV (£)" → "GBP")
+- The `breakclause` SHALL default to "N" if not explicitly mentioned in the email
+- The `pv` SHALL be the numeric present value without formatting (no commas, no currency symbols)
+
+#### Scenario: Flatten multi-leg swap into individual items
+
+- **WHEN** the email contains a swap with Coupon Leg (Murex 79353083) and APD leg (Murex 79353084)
+- **THEN** the output contains two separate TradeItems, one per Murex ID
+
+#### Scenario: Currency symbol to ISO code mapping
+
+- **WHEN** the email shows PV values in "PV (£)" column
+- **THEN** the `display_ccy` field is set to "GBP"
+
+#### Scenario: Default breakclause
+
+- **WHEN** the email does not mention break clauses
+- **THEN** all TradeItems have `breakclause` set to "N"