fix: reverse proxy compatibility (header case + port 0 in mds.js)

[astowny]

Problem

When Minima's MDS (MiniDapp System) runs behind a reverse proxy like Traefik, nginx, or HAProxy, two bugs prevent MiniDapps from working:

Bug 1: Case-sensitive HTTP header parsing (MDSFileHandler.java)

All POST requests fail with "Connection failed: Your session is invalid".

MDSFileHandler.java stores HTTP headers with their original case but looks them up with exact case "Content-Length". Per RFC 7230 §3.2, HTTP/1.1 headers are case-insensitive, and per RFC 7540 §8.1.2, HTTP/2 mandates lowercase. When a reverse proxy forwards content-length (lowercase):

1. allheaders.get("Content-Length") → null
2. Integer.parseInt(null) → NumberFormatException
3. Caught by generic catch(Exception) → returns invalid.html
4. MiniDapp JS does JSON.parse(html) → "Connection failed"

Bug 2: ERR_UNSAFE_PORT in MiniDapp mds.js copies

When accessing via standard HTTPS (port 443), window.location.port returns "". Math.floor("") evaluates to 0, producing URLs like https://host:0/mdscommand_/.... Browsers block port 0 → ERR_UNSAFE_PORT → black screen.

The main mds/mds.js already has the fix (if(port == 0) check), but 41 copies in mds/code/*/mds.js still had the old code.

Fixes

Commit 1: MDSFileHandler.java

Added normalizeHeaderName() that converts HTTP header names to canonical form (content-length → Content-Length) when parsing. Follows standard HTTP convention: capitalize first letter and every letter after a hyphen.

Commit 2: mds/code/*/mds.js (41 files)

Added if(port == 0) check to omit the port from URLs when running on standard ports (443/80), matching the fix already present in the main mds/mds.js.

Testing

• Direct access (no proxy) — ✅ works as before
• Behind Traefik 3.x with HTTP/2 → HTTP/1.1 — ✅ both bugs fixed
• curl with lowercase headers — ✅ handled correctly
• Standard HTTPS port (443) — ✅ no more ERR_UNSAFE_PORT

Files Changed

• src/org/minima/system/mds/MDSFileHandler.java — Header name normalization
• mds/code/*/mds.js (41 files) — Port 0 handling