Polish: reconcile spec fields, code quality, expanded tests, updated README

- Controller: use spec.image (default ollama/ollama:latest) and expose
  spec.model as MODEL env var in the container
- Controller: extract buildService helper; use spec.port and
  spec.serviceType; reconcile Service drift on update
- MCP tools: add context.Context propagation throughout (replaces
  context.Background()); safe model arg extraction via modelFromArgs
  (prevents panic on missing/wrong-type input)
- MCP server: update ToolHandler signature to accept context.Context;
  pass r.Context() from HTTP handlers
- Tests: replace single boilerplate test with 11 targeted specs covering
  image override, MODEL env var, port/serviceType defaults and overrides,
  service drift reconciliation, idempotency, and missing resource handling
- README: rewrite for clarity; add field behaviour table, test dry run
  output, and honest notes on NL interface and tool server protocol

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: ShaunakJoshi1407