feat(mods): replace packwiz with distribution-fed custom mod volume

Drop packwiz entirely. The server now loads a filtered mod subset from a
local ./server-mods volume instead of fetching a packwiz pack at boot.

New flow:
- tooling/classify-mods.py (tomllib only, no network) reads each jar's
  META-INF/neoforge.mods.toml and seeds mods-sides.json with a side
  (client|server|both; default both). Existing entries are preserved.
- mods-sides.json: committed, keyed by jar filename, hand-editable override
  surface. Initial seed: 65 both, 11 client, 0 server (76 jars).
- tooling/sync-server-mods.sh mirrors the both/server jars from
  $DISTRIBUTION_WEB_ROOT into ./server-mods/ (authoritative; prunes strays;
  halts on a missing jar). Replaces render-pack.sh.
- compose: minecraft mounts ./server-mods:/mods:ro with REMOVE_OLD_MODS=TRUE
  (itzg auto-syncs /mods -> /data/mods). Removed PACKWIZ_URL, the pack.
  extra_host (auth. kept for authlib), and depends_on caddy (drasl kept).

Both classify-mods.py and sync-server-mods.sh resolve their source dir as:
CLI arg / MODS_DIST_DIR env / $DISTRIBUTION_WEB_ROOT (in that order).

Removed: tooling/render-pack.sh + add-custom-mod.sh (packwiz tooling),
pack/ (packwiz source), custom/ (76 jars now sourced from the distribution),
the pack. caddy vhost + its mounts/alias, and the packwiz .gitignore block.

Client distribution is UNCHANGED: HeliosLauncher still installs the full
modset from distribution.json. Docs (CLAUDE.md, plan/04/05/14, runtime)
updated; plan/04-packwiz.md stubbed as superseded by plan/04-mods.md.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

plan/04-packwiz.md

@@ -1,37 +1,7 @@
-# packwiz — modpack source of truth
+# packwiz — modpack source of truth (SUPERSEDED)
 
-## Summary
-
-`packwiz` (installed at `~/go/bin/packwiz`) authors the modpack. The `./pack`
-directory is the **single source of truth** for mods, consumed by both:
-- the **server** (itzg `PACKWIZ_URL`), and
-- **clients** (Fjord launcher imports the pack / packwiz-installer).
-
-Caddy serves `./pack` at `pack.ulicraft.net`. packwiz emits **metadata**
-(`pack.toml`, `index.toml`, `mods/*.pw.toml`); the `.pw.toml` files reference
-Modrinth/CF **CDN URLs**, so server and clients fetch the jars from those CDNs.
-The stack assumes the internet is present.
-
-## Behaviors confirmed
-
-- **Prune**: packwiz-installer tracks a manifest and **removes** client mods no
-  longer in the index on re-run. (Server side via itzg likewise re-syncs.)
-- **Download source**: jars come from the CDN URLs in `.pw.toml`, not the pack
-  host (which serves only metadata).
-- **itzg side filtering**: itzg downloads **server-side mods only**. Client-only
-  mods MUST be tagged `side = "client"` (not `both`) or the server may pull and
-  crash on them.
-
-## NeoForge pinning
-
-`pack.toml` pins MC `1.21.1` + NeoForge `21.1.x`. Verify exact NeoForge build
-against projects.neoforged.net before locking.
-
-## Tasks
-
-- [ ] `packwiz init` → `./pack` (MC 1.21.1, modloader neoforge, pinned version)
-- [ ] Curate mod shortlist (perf/tech/magic/storage/QoL/worldgen/map/voice)
-- [ ] Tag client-only mods `side = "client"`
-- [ ] `packwiz refresh`; verify `index.toml` committed (clients fetch it)
-- [ ] Point server `PACKWIZ_URL=http://pack.ulicraft.net/pack.toml`
-- [ ] Test install end-to-end on a fresh client
+> **Superseded by [`04-mods.md`](04-mods.md).** packwiz has been removed.
+> The server now loads a filtered mod subset from a local `server-mods/` volume
+> (synced from the distribution repo by `tooling/sync-server-mods.sh`); clients
+> still get the full set from the HeliosLauncher `distribution.json`.
+> See `04-mods.md` for the current design.