fix: derive version from git tags instead of package.json (#486)

## Summary

Fixes #485 — the app version was derived from `package.json` via
Node.js, which is a meaningless artifact for this Go project. This
caused version mismatches (e.g., v3.3.0 release showing "3.2.0") when
someone forgot to bump `package.json`.

## Changes

### `manage.sh`
- **Line 43**: Replace `node -p "require('./package.json').version"`
with `git describe --tags --match "v*"` — version is now derived
automatically from git tags
- **Line 515**: Add `--force` to `git fetch origin --tags` in setup
command
- **Line 1320**: Add `--force` to `git fetch origin --tags` in update
command — prevents "would clobber existing tag" errors when tags are
moved

### `package.json`
- Version field set to `0.0.0-use-git-tags` to make it clear this is not
the source of truth. File kept because npm scripts and devDependencies
are still used for testing.

## How it works

`git describe --tags --match "v*"` produces:
- `v3.3.0` — when on an exact tag
- `v3.3.0-3-gabcdef1` — when 3 commits after a tag (useful for
debugging)
- Falls back to `unknown` if no tags exist

## Testing

- All Go tests pass (`cmd/server`, `cmd/ingestor`)
- All frontend unit tests pass (254/254)
- No changes to application logic — only build-time version derivation

Co-authored-by: you <you@example.com>

manage.sh

@@ -40,7 +40,7 @@ STAGING_DATA="${STAGING_DATA_DIR:-$HOME/meshcore-staging-data}"
 STAGING_COMPOSE_FILE="docker-compose.staging.yml"
 
 # Build metadata — exported so docker compose build picks them up via args
-export APP_VERSION=$(node -p "require('./package.json').version" 2>/dev/null || echo "unknown")
+export APP_VERSION=$(git describe --tags --match "v*" 2>/dev/null || echo "unknown")
 export GIT_COMMIT=$(git rev-parse --short HEAD 2>/dev/null || echo "unknown")
 export BUILD_TIME=$(date -u +%Y-%m-%dT%H:%M:%SZ)
 
@@ -512,7 +512,7 @@ cmd_setup() {
 
   # Default to latest release tag (instead of staying on master)
   if ! is_done "version_pin"; then
-    git fetch origin --tags 2>/dev/null || true
+    git fetch origin --tags --force 2>/dev/null || true
     local latest_tag
     latest_tag=$(git tag -l 'v*' --sort=-v:refname | head -1)
     if [ -n "$latest_tag" ]; then
@@ -1317,7 +1317,7 @@ cmd_update() {
   local version="${1:-}"
 
   info "Fetching latest changes and tags..."
-  git fetch origin --tags
+  git fetch origin --tags --force
 
   if [ -z "$version" ]; then
     # No arg: checkout latest release tag

package.json

@@ -1,6 +1,6 @@
 {
   "name": "meshcore-analyzer",
-  "version": "3.3.0",
+  "version": "0.0.0-use-git-tags",
   "description": "Community-run alternative to the closed-source `analyzer.letsmesh.net`. MQTT packet collection + open-source web analyzer for the Bay Area MeshCore mesh.",
   "main": "index.js",
   "scripts": {