Change default port from 8080 to 7334 (NGIT on phone keypad)

- Update default bind address in src/config.rs to 127.0.0.1:7334
- Update all four critical config sources per AGENTS.md:
  - src/config.rs (code default and tests)
  - .env.example (development template)
  - docs/reference/configuration.md (user documentation)
  - nix/module.nix (NixOS deployment)
- Update all documentation examples and references:
  - README.md (with note about phone keypad mnemonic)
  - docs/how-to/*.md (deploy, prometheus-setup, test-compliance)
  - docs/explanation/*.md (architecture, comparison)
  - docs/learnings/grasp-audit.md

Port 7334 spells NGIT on a phone keypad, making it memorable and
project-specific.

All tests pass (336 lib tests + 51 integration tests).

1 files changed, 1 insertions, 1 deletions

diff --git a/nix/module.nix b/nix/module.nix
index 799ae2d..ae67512 100644
--- a/nix/module.nix
+++ b/nix/module.nix
@@ -43,7 +43,7 @@ let
 
       port = mkOption {
         type = types.port;
-        default = 8080;
+        default = 7334;
         description = "Port to listen on";
       };