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).

2 files changed, 2 insertions, 2 deletions

diff --git a/docs/explanation/architecture.md b/docs/explanation/architecture.md
index d2a9bf7..e101425 100644
--- a/docs/explanation/architecture.md
+++ b/docs/explanation/architecture.md
@@ -580,7 +580,7 @@ RUN cargo build --release
 FROM debian:bookworm-slim
 RUN apt-get update && apt-get install -y git && rm -rf /var/lib/apt/lists/*
 COPY --from=builder /app/target/release/ngit-grasp /usr/local/bin/
-EXPOSE 8080
+EXPOSE 7334
 CMD ["ngit-grasp"]
 ```
 
diff --git a/docs/explanation/comparison.md b/docs/explanation/comparison.md
index 72e49a7..090e0eb 100644
--- a/docs/explanation/comparison.md
+++ b/docs/explanation/comparison.md
@@ -65,7 +65,7 @@ This document compares ngit-grasp (this project) with ngit-relay (the reference
 ┌────────────── ngit-grasp (Single Binary) ─────────────┐
 │                                                        │
 │  ┌──────────────────────────────────────────────────┐ │
-│  │         hyper HTTP Server (:8080)                 │ │
+│  │         hyper HTTP Server (:7334)                 │ │
 │  │  - WebSocket upgrade for Nostr relay              │ │
 │  │  - Git Smart HTTP handlers                        │ │
 │  │  - Landing page + metrics endpoint                │ │