chore: initial commit — UdyamLinc backend, phases A-E

Spring Boot 4 / Java 17 / Postgres. Masters and serving (A), Agmarknet and
climate ingestion (B), feature store with 14 derivations (C), SpEL rule
engine and risk scoring (D).

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,29 @@
+# Build output
+target/
+*.jar
+*.war
+
+# Secrets — the data.gov.in key and any local credential override live in the
+# environment, never in the repo. application-local.properties is the escape
+# hatch for developers who want them on disk.
+.env
+.env.*
+application-local.properties
+application-local.yml
+src/main/resources/application-local.properties
+
+# IDE
+.idea/
+*.iml
+.vscode/
+.settings/
+.project
+.classpath
+
+# OS
+.DS_Store
+Thumbs.db
+
+# Logs
+*.log
+logs/