feat: add interval projection schema and models

Add time-series tracking tables for animal location, tag, and attribute
history. Each interval represents a period when an animal had a specific
state, with open intervals (end_utc=NULL) for current state.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

migrations/0004-interval-projections.sql

@@ -0,0 +1,56 @@
+-- ABOUTME: Creates interval projection tables for time-series tracking.
+-- ABOUTME: Tracks animal location, tag, and attribute history over time.
+
+-- Track animal location history
+-- Each row represents a period when an animal was at a specific location
+CREATE TABLE animal_location_intervals (
+    animal_id TEXT NOT NULL CHECK(length(animal_id) = 26),
+    location_id TEXT NOT NULL CHECK(length(location_id) = 26),
+    start_utc INTEGER NOT NULL,
+    end_utc INTEGER,
+    PRIMARY KEY (animal_id, start_utc),
+    CHECK(end_utc IS NULL OR end_utc > start_utc)
+);
+
+-- Index for "which animals were at location X at time T" queries
+CREATE INDEX idx_ali_loc_time ON animal_location_intervals(
+    location_id, start_utc, COALESCE(end_utc, 32503680000000)
+);
+
+-- Index for "where was animal X at time T" queries
+CREATE INDEX idx_ali_animal_time ON animal_location_intervals(
+    animal_id, start_utc, COALESCE(end_utc, 32503680000000)
+);
+
+-- Track animal tag history
+-- Each row represents a period when an animal had a specific tag
+CREATE TABLE animal_tag_intervals (
+    animal_id TEXT NOT NULL CHECK(length(animal_id) = 26),
+    tag TEXT NOT NULL,
+    start_utc INTEGER NOT NULL,
+    end_utc INTEGER,
+    PRIMARY KEY (animal_id, tag, start_utc),
+    CHECK(end_utc IS NULL OR end_utc > start_utc)
+);
+
+-- Index for "which animals had tag X at time T" queries
+CREATE INDEX idx_ati_tag_time ON animal_tag_intervals(
+    tag, start_utc, COALESCE(end_utc, 32503680000000)
+);
+
+-- Track attribute changes (sex, life_stage, repro_status, status)
+-- Each row represents a period when an animal had a specific attribute value
+CREATE TABLE animal_attr_intervals (
+    animal_id TEXT NOT NULL CHECK(length(animal_id) = 26),
+    attr TEXT NOT NULL CHECK(attr IN ('sex', 'life_stage', 'repro_status', 'status')),
+    value TEXT NOT NULL,
+    start_utc INTEGER NOT NULL,
+    end_utc INTEGER,
+    PRIMARY KEY (animal_id, attr, start_utc),
+    CHECK(end_utc IS NULL OR end_utc > start_utc)
+);
+
+-- Index for "which animals had attr=value at time T" queries
+CREATE INDEX idx_aai_attr_time ON animal_attr_intervals(
+    attr, value, start_utc, COALESCE(end_utc, 32503680000000)
+);