Species identity and O.C.C. eligibility foundation

[StreamDemon]

First prerequisite for #57 under umbrella #12. This issue becomes the sole next-up task.

Goal: introduce the minimum reusable species and O.C.C.-eligibility foundation without pulling Psi-Stalker, R.C.C., or psionics content into the Coalition Grunt slice.

Approved boundary:

• add a small species catalog with Human playable and Psi-Stalker recorded as a deferred, nonplayable identity from p.233;
• treat Human as the compatibility default for legacy characters without rewriting stored documents;
• replace free-text racial requirements with structured any or oneOf O.C.C. species eligibility and content-load validation;
• prove the printed Coalition Grunt Human/Psi-Stalker restriction with a focused p.233 test fixture while keeping production Grunt content in Coalition Grunt O.C.C.: second playable class foundation #57;
• add one pure eligibility validator reused by builder, deriveSheet, and backend writes for species and attributes;
• preserve pure derivation and reject unknown or unavailable ids.

Authoritative rules evidence for the first consumer comes from rendered RUE p.233. Any additional printed mechanics must be rendered and page-stamped; do not infer them from memory.

Explicitly out of scope: playable Psi-Stalker content, R.C.C. mechanics, I.S.P./psychic powers (#14), Coalition Grunt content itself (#57), S.D.C./skill effects, and starting loadouts.

Success requires rules/backend/web package gates, root gates, focused compatibility tests, and live browser verification of the locked Human identity and resolved sheet display. No existing character document is rewritten.

Predecessor: none.
Successor: #61, then #62, then #57.

Builder presentation: show Human as a locked identity field while it is the only playable species; do not add an otherwise empty wizard step.

[StreamDemon]

Draft PR: #63

Final branch SHA: 4b3574443e00167e2433be97383183598e8eb3a1

Validation on the final revision:

• vp check: 139/139 files formatted; 101 lint/typecheck files clean
• vp test: 26/26 files; 559/559 tests passed
• rules package: check clean; 370/370 tests passed
• backend package: check clean; 131/131 tests passed
• web package: check clean; 58/58 tests passed
• git diff --check: clean
• final independent review: approved with no remaining findings

Live browser acceptance covered the production revision (the final follow-up commit is test-only):

• HUMAN // LOCKED identity with no species picker
• legal Ley Line Walker shared eligibility and full forge flow
• Human persisted through sheet navigation and reload
• vitals roll and legal spell cast
• same-document dossier navigation without stale command state
• 390x844 and desktop layouts without horizontal overflow
• keyboard traversal and non-color disabled-O.C.C. explanation
• zero browser console errors or warnings

Local Convex/web processes were stopped, ports 3210/5173 were confirmed closed, and temporary render/browser artifacts were removed. #60 remains the sole active next-up; downstream dependency labels are unchanged pending human merge and synchronized-main verification.