fix: Configure dbt to use local profiles.yml

- Rename profiles.yml.example to profiles.yml (uses env vars, safe to commit)
- Add --profiles-dir flag to dbt commands in load_toronto_data.py
- Add --profiles-dir flag to dbt targets in Makefile

This fixes the "Path '~/.dbt' does not exist" error when running make load-data.

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

dbt/profiles.yml

@@ -0,0 +1,21 @@
+toronto_housing:
+  target: dev
+  outputs:
+    dev:
+      type: postgres
+      host: localhost
+      user: portfolio
+      password: "{{ env_var('POSTGRES_PASSWORD') }}"
+      port: 5432
+      dbname: portfolio
+      schema: public
+      threads: 4
+    prod:
+      type: postgres
+      host: "{{ env_var('POSTGRES_HOST') }}"
+      user: "{{ env_var('POSTGRES_USER') }}"
+      password: "{{ env_var('POSTGRES_PASSWORD') }}"
+      port: 5432
+      dbname: portfolio
+      schema: public
+      threads: 4