chore(skills): extend /pr-push with rebase + regen + stage for generator branches

Adds a new step 4a that detects generator-source or economy-data changes
vs origin/main and runs `make regen-db` before the push, staging the
updated systems.db. Pairs with the pre-push hook (#857) — instead of
rejecting a stale DB, /pr-push proactively freshens it.

Refs: #858

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.claude/skills/pr-push/SKILL.md

@@ -26,6 +26,20 @@ current branch — never touches main.
 
 ## Workflow
 
+### 0. Dry-run mode check
+
+If the user invokes `/pr-push --dry-run`:
+- Print: "Dry-run mode — inspecting state, nothing will be pushed or committed."
+- Run steps 1 through 4a in **inspect-only** mode:
+  - Step 4: run `make check-systems-db` to check current stamp freshness (no merge)
+  - Step 4a: report which watched files changed vs origin/main; show whether `make regen-db`
+    would be triggered; do NOT run the regen, stage, or commit
+- Print a summary: watched files changed (list), regen needed (yes/no), DB stamp fresh (yes/no)
+- Print "Dry run complete — use /pr-push to apply."
+- Stop. Do not push or create a PR.
+
+---
+
 ### 1. Validate branch
 
 ```bash
@@ -201,6 +215,67 @@ git merge origin/main --no-edit
 If merge conflicts, **stop and report** — let the user resolve.
 If clean, continue.
 
+### 4a. Regen systems.db if generator sources or data changed (#858)
+
+Check whether any file in the **source-file watch list** was modified on this branch
+versus `origin/main`. This list covers generator code AND the data files that feed them:
+
+```bash
+git diff --name-only origin/main...HEAD -- \
+  tooling/economy-db/import_economics.py \
+  tooling/planet-gen/generate_atlas.py \
+  server/src/bin/generate_brands/main.rs \
+  tooling/generate-brands \
+  server/data/systems-schema.sql \
+  wiki/star-systems/ \
+  wiki/economics/ \
+  content/economics/
+```
+
+**If output is empty:** skip this step entirely.
+
+**If any files appear in the output:** the DB must be regenerated on top of the
+current main. Perform the following:
+
+1. **Integrate main.** Step 4 merged main into the branch. If you find yourself
+   on a branch that was NOT yet merged with main in step 4, do it now:
+   ```bash
+   git fetch origin
+   git merge origin/main --no-edit
+   ```
+   If there are merge conflicts in source files, **stop and report which files
+   conflict**. Ask the user to resolve manually — do not attempt to auto-resolve
+   generator source conflicts.
+
+2. **Regenerate the DB:**
+   ```bash
+   make regen-db
+   ```
+   `make regen-db` runs all three generators and stamps the meta table. It tolerates
+   coverage gate failures (exit 2 = data quality warning, not an error). If it exits
+   with any other non-zero code, stop and report the stderr output — do not push.
+
+3. **Stage the updated DB:**
+   ```bash
+   git add server/data/systems.db
+   ```
+
+4. **Commit only if the DB actually changed:**
+   ```bash
+   git diff --cached --stat -- server/data/systems.db
+   ```
+   - If the diff shows changes: commit with `/git-commit`, message:
+     `chore(db): regen systems.db against rebased sources`
+   - If no diff (regen produced identical output — sources were self-consistent):
+     unstage the file (`git restore --staged server/data/systems.db`) and skip the
+     commit. The source changes alone are the PR content.
+
+**In dry-run mode** (from step 0): report which watch-list files changed and
+whether regen would be triggered. Do NOT run the regen or modify any files.
+
+This step prevents the pre-push hook from rejecting a push where the branch modifies
+a generator source or data file but did not regenerate the DB.
+
 ### 5. Push
 
 ```bash