docs(P01): complete Orgs+Window foundation phase

---ci---
project: oy
phase: 1
milestone: v0.2
status: complete
phase_role: execution
requirements:
  covered: [REQ-015, REQ-016, REQ-017, REQ-012]
  partial: []
---/ci---

Phase 1 (Orgs+Window foundation) complete. 3 new modules (x/window, x/stand, x/guild)
+ lexicon meta-test scaffolding (G-004). 143 tests total (53 v0.1 baseline + 90 new), 100%
coverage on new packages. Window = fullest primitive (lifecycle Open->Active->Revoked->
Expired, rate-limit, append-only audit log). 9-type Stand enum. Guild Hand-Pass @ 0% fee.
G-003 by-ID-string import invariant test green. G-004/G-009 lexicon meta-test + self-test
table green. Tagged v0.1.1.

lexicon/lexicon.go

@@ -0,0 +1,87 @@
+// Package lexicon holds the project-wide lexicon firewall (REQ-012).
+//
+// The 9 banned financial terms must never appear in any production or test
+// .go file under x/. This package exposes the banned-terms list and detection
+// helpers; the terms themselves are assembled at runtime from two-character
+// fragments so that the SOURCE of this package does not contain any banned
+// term as a literal substring. This is the standard lexicon-test bootstrapping
+// pattern: the firewall's own code must not trip the firewall.
+//
+// The lexicon firewall is NEW in v0.2 (G-002): v0.1 is lexicon-clean in
+// practice but has zero lexicon tests. The project-wide meta-test in
+// P1-04-02 (lexicon_meta_test.go) is the durable firewall; per-package
+// lexicon assertions in each new module's types_test.go scan the module's
+// production files.
+package lexicon
+
+import (
+	"regexp"
+	"strings"
+)
+
+// term is a banned term assembled from two halves so the source file does
+// not contain the literal banned word.
+type term struct {
+	a, b string
+}
+
+// fragments holds the 9 banned terms as (a, b) halves. Neither half alone
+// is a banned term, and concatenation produces the banned term at runtime.
+var fragments = []term{
+	{"ba", "nk"},      // bank
+	{"depo", "sit"},   // deposit
+	{"intere", "st"},  // interest
+	{"yie", "ld"},     // yield
+	{"curre", "ncy"},  // currency
+	{"dol", "lar"},    // dollar
+	{"eu", "ro"},      // euro
+	{"acco", "unt"},   // account
+	{"savin", "gs"},   // savings
+	{"deposito", "r"}, // depositor
+}
+
+// BannedTerms returns the banned financial terms (REQ-012). The spec lists
+// 10 terms (often described as "9" in plan docs, counting dollar/euro as a
+// pair): bank, deposit, interest, yield, currency, dollar, euro, account,
+// savings, depositor. The terms are assembled at runtime from fragments so
+// this package's source does not contain any banned term as a literal
+// substring.
+func BannedTerms() []string {
+	out := make([]string, len(fragments))
+	for i, t := range fragments {
+		out[i] = t.a + t.b
+	}
+	return out
+}
+
+// bannedTermRegexes are the compiled word-boundary regexes for the 9 banned
+// terms. Word boundaries prevent false positives like "openyield" matching
+// "yield" or "european" matching "euro" — the firewall bans the words as
+// concepts, not as arbitrary substrings. The regexes are case-insensitive.
+var bannedTermRegexes = func() []*regexp.Regexp {
+	terms := BannedTerms()
+	out := make([]*regexp.Regexp, len(terms))
+	for i, t := range terms {
+		out[i] = regexp.MustCompile(`\b` + regexp.QuoteMeta(t) + `\b`)
+	}
+	return out
+}()
+
+// FindBannedTerm returns the first banned term found in s (case-insensitive,
+// word-boundary match) and true, or "" and false if none. Used by the
+// project-wide meta-test (P1-04-02) and the per-package lexicon assertions.
+func FindBannedTerm(s string) (string, bool) {
+	lower := strings.ToLower(s)
+	terms := BannedTerms()
+	for i, re := range bannedTermRegexes {
+		if re.MatchString(lower) {
+			return terms[i], true
+		}
+	}
+	return "", false
+}
+
+// ContainsBannedTerm is an alias for FindBannedTerm kept for compatibility.
+func ContainsBannedTerm(s string) (string, bool) {
+	return FindBannedTerm(s)
+}