Add buy/sell tools, library docs, and permit/HQ fixes

- tools/buy.py: cash-aware shopping list (construction gap vs empire state's built
  buildings, plus N days of NET operating stock via simulate() so self-produced
  inputs net against consumption), priced at real order-book fill cost, checked
  against cash/reserve, flags multi-trip, binary-searches an affordable size when short
- tools/sell.py: where to post an ask vs hitting the bids now, with expected
  clear time from 30-day traded-volume percentiles
- docs/library.md: module map and patterns for using puga.* directly instead of
  the CLI, plus the "simulate() only knows what the plan lists" gotcha that a
  first version of buy.py hit
- tools/simulate.py: fix --no-hq being a no-op; tools/state.py: permits_total_override
  for when the in-game HQ screen disagrees with FIO's MaximumPermits
- docs/mechanics.md: HQ display vs PRUNplanner's HQ flag, workforce arrival sources
- CLAUDE.md, docs/roadmap.md updated

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

CLAUDE.md

@@ -32,6 +32,9 @@ Agent-first toolkit for advising a Prosperous Universe player. The player asks q
 - `puga/` library; `tools/` CLIs; `plans/examples/` generic plan specs (also test fixtures); `state/company.example.yaml` example state; `tests/`; `data/` (gitignored fetched data cache); `ref/` (gitignored PRUNplanner source).
 - Rule: game facts and generic methods go in `docs/`; anything about the player's own bases, cash, decisions or preferences goes in `empire/`.
 
+## Library use (not just CLI)
+For anything the CLI tools don't expose (custom what-ifs, cost breakdowns with wages/capex, ad-hoc market checks) import `puga.*` directly in a short inline script instead of stretching a tool's flags. See `docs/library.md` for the module map and patterns; most non-trivial answers in this project came from a `python - <<EOF` block, not a CLI flag.
+
 ## Tools
 Run as `puga <tool> ...` (e.g. `puga scan --min-n 3`, `puga plan pull <uuid>`); the `tools/x.py` paths below are the same programs.
 - `tools/state.py sync|show` refreshes `empire/state/company.yaml` from live FIO (cash, permits, buildings, real production efficiency, storage, ships).
@@ -39,6 +42,8 @@ Run as `puga <tool> ...` (e.g. `puga scan --min-n 3`, `puga plan pull <uuid>`);
 - `tools/simulate.py <spec.yaml | --uuid U> [--off EXT,SME] [--basis real|uni30|vwap30|ask|...]` replica of PRUNplanner's simulator (efficiency, workforce, material I/O, profit). Flows and efficiency verified exact vs screenshots; profit within ~2%. The NEW CAPEX line = planned minus already built (from state), the honest payback; ignore the plan-level ROI (PRUNplanner always adds a core module). `--uuid` reads the SAVED plan from the account (UI edits must be saved first).
 - `tools/scan.py` DEPTH-AWARE recipe scan (use this): buildings the market could absorb, ROI for our own size, patient prices, ask-walked inputs. Fully staffed AND understaffed variants by default (`--staffing`), freight netted out (`--trip-cost`, `--cargo`), HQ/COGC/experts/faction, `--planet ID` adds that planet's extraction, fertility and COGC (a planet not in state is a new base: no HQ, permits+1), `--deprec 60` prices demolish-later. `--min-n` is ONLY a noise filter on market capacity (use 3, ideally 10); ROI is always for our own size (`--own`, default 1 building), never at the filtered scale. Below 1 lets sub-building junk in. `--json rows.json` feeds `persistence.py`. Library: `puga/saturation.py`.
 - `tools/history.py TICKER` monthly margin history of the recipe producing TICKER; `tools/persistence.py rows.json` re-prices scan rows over history (mean ROI 7/14/30/90/180d, payback, net gain over 7 and 14 days, % days profitable). ALWAYS check persistence before recommending: current margins are often a spike.
+- `tools/buy.py <spec.yaml|--uuid U> --days N` cash-aware shopping list: construction gap (plan vs empire state's built buildings) plus N days of the plan's NET operating stock (via `simulate()`, so self-produced inputs like AL net against consumption), priced at real fill cost, checked against cash/reserve. Pass a plan covering the WHOLE base for restocking, not just a new addition (see `docs/library.md`).
+- `tools/sell.py TICKER QTY` where to post an ask (undercutting the current best) vs hitting the bids now, plus expected hours to clear from 30-day traded-volume percentiles.
 - `tools/chain.py TICKER` make-vs-buy cost tree plus sourcing depth of inputs.
 - `tools/price.py` prices across exchanges with VWAP, volume, fill price for a quantity; `tools/book.py` order-book ladder.
 - `tools/prun_scan.py`, `tools/prun_cxarb.py` legacy top-of-book scans; overstate thin markets. Baseline only. `tools/arb.py` replacement is on the roadmap.