cleanup: remove binaries and build artifacts from git tracking

Remove large files that should not be committed:
- insertr binary (19MB) - generated Go executable
- test-output/ and client-dist/ - build output directories
- demo-site/insertr.js - generated from lib/dist/insertr.js
- internal/content/assets/*.js - embedded build artifacts
- outdated integration/version control summary files
- log files (server.log)

Update .gitignore to exclude:
- Compiled binaries (insertr, insertr.exe)
- Generated assets (demo-site/insertr.js, internal/content/assets/*.js)
- Build output directories (test-output/, client-dist/)
- Database files (*.db) and log files (*.log)
- Air temporary files

Repository size reduction: ~20MB+ of unnecessary tracked files removed

AGENTS.md

@@ -1,6 +1,7 @@
 # AGENTS.md - Developer Guide for Insertr
 
 ## Build/Test Commands
+Let me handle running and building the server. I run just dev in a different terminal, so you can just test the api directly, without spinning up an instance.
 - `just dev` - Full-stack development (recommended)
 - `just build` - Build entire project (Go binary + JS library)
 - `just build-lib` - Build JS library only
@@ -28,4 +29,4 @@
 ### Database
 - Use `sqlc` for Go database code generation
 - SQL files in `db/queries/`, schemas in `db/{sqlite,postgresql}/schema.sql`
-- Run `just sqlc` after schema changes
+- Run `just sqlc` after schema changes