fix(client): bake the version into the build, so an export can invalidate its cache (T-1241)

current_schema_version() line-scanned res://../project.yaml at runtime. That
resolves to the repo root in a dev run and to nothing in an exported build, so a
shipped game got the "?.?.?" fallback every time. Since that tag is the Atlas
disk cache's ONLY invalidation signal, every exported build stamped and compared
the same sentinel: a canvas cached by one build would be served by every later
build, forever. T-1239 is what that failure looks like once it happens.

loading_screen.gd carried a byte-for-byte copy of the same function, so the
version shown to the player was "?.?.?" in exactly the builds where a version
string is worth showing. Both call sites now share client/scripts/build_version.gd,
which reads application/config/version out of ProjectSettings — a value Godot
bakes into the PCK, identical in the editor and in an export by construction
rather than by luck. No file IO, no fallback branch.

project.yaml stays the source of truth (CLAUDE.md); client/project.godot mirrors
it. A mirror nobody checks would be worse than the bug it replaces -- the old
code failed loudly everywhere, a stale mirror fails silently -- so
tooling/check-client-version compares the two and the pre-push hook runs it
unconditionally. Not gated on "were those files in this push": drift persists on
main once introduced, and gating would let an existing drift ride along.

The test this replaces asserted that current_schema_version() did not return its
fallback, and passed -- in the one environment where the code under test worked.
Three tests now pin the property that actually matters: a real version, sourced
from the baked setting, matching project.yaml.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

.pql/changelog/ticket_history/2026-08.sql

@@ -169,3 +169,4 @@ FOLLOW-UPS worth their own tickets, not done here:
   suggests a check (e.g. a pre-push rule: canvas-generation paths touched =>
   project.yaml version must move) rather than a fifth comment.', NULL, '2026-08-14 21:13:15', '2026-08-14 21:13:15.779', '2026-08-14 21:13:15.779', NULL, 'a7cfa7d53e62cff64cd95b5738d1ee75', 2) ON CONFLICT(hash) DO NOTHING;
 INSERT INTO ticket_history (ticket_record_id, field, old_value, new_value, changed_by, changed_at, created_at, updated_at, deleted_at, hash, canonical_version) VALUES ('06FXF1VDVQDQ8EFGTXX787M90R', 'status', 'in_progress', 'done', NULL, '2026-08-14 21:20:27', '2026-08-14 21:20:27.835', '2026-08-14 21:20:27.835', NULL, '815c19499dbf40e3b7a79f44c09089c2', 2) ON CONFLICT(hash) DO NOTHING;
+INSERT INTO ticket_history (ticket_record_id, field, old_value, new_value, changed_by, changed_at, created_at, updated_at, deleted_at, hash, canonical_version) VALUES ('06G0495WRHF8ADK82VR8CH1J8R', 'status', 'backlog', 'in_progress', NULL, '2026-08-14 21:21:35', '2026-08-14 21:21:35.098', '2026-08-14 21:21:35.098', NULL, 'caa82c705ee32a7582705b2dd5d2cf17', 2) ON CONFLICT(hash) DO NOTHING;

.pql/changelog/tickets/2026-08.sql

@@ -302,3 +302,4 @@ FOLLOW-UPS worth their own tickets, not done here:
 - Nothing enforces the generation-change/version-bump pairing. Four occurrences
   suggests a check (e.g. a pre-push rule: canvas-generation paths touched =>
   project.yaml version must move) rather than a fifth comment.', 'done', 'high', NULL, 'client', 'D-261', '2026-08-06 14:43:24.765', '2026-08-14 21:20:27.835', NULL, 'fa2402988b35d9f0db6ffcf7cf7a81c2', 2) ON CONFLICT(record_id) DO UPDATE SET type=excluded.type, parent_record_id=excluded.parent_record_id, title=excluded.title, description=excluded.description, status=excluded.status, priority=excluded.priority, assigned_to=excluded.assigned_to, team=excluded.team, decision_ref=excluded.decision_ref, updated_at=excluded.updated_at, deleted_at=excluded.deleted_at, hash=excluded.hash, canonical_version=excluded.canonical_version WHERE excluded.updated_at >= tickets.updated_at;
+INSERT INTO tickets (record_id, type, parent_record_id, title, description, status, priority, assigned_to, team, decision_ref, created_at, updated_at, deleted_at, hash, canonical_version) VALUES ('06G0495WRHF8ADK82VR8CH1J8R', 'bug', '06FB0TNSRZXCHGS16BFHSSGSV4', 'Atlas disk cache never invalidates in an exported build — current_schema_version() falls back to ''?.?.?''', 'step_canvas_disk_cache.gd::current_schema_version() reads ProjectSettings.globalize_path(''res://'') + ''/../project.yaml''. That resolves to the repo-root file in a dev run (res:// = client/), but an exported build has no project.yaml one level above res://, so the function returns its ''?.?.?'' fallback. Every exported build therefore stamps and compares the SAME sentinel version, which means the schema-version invalidation path — the cache''s only invalidation signal — is inert in a shipped game: a canvas cached by one build is served forever by every later build. Found while diagnosing T-1239, where the same mechanism failed in dev for a different reason (the version simply was not bumped). Fix direction: bake the version into the client at export time (a generated const, ProjectSettings application/config/version, or an exported resource) rather than reading a repo file at runtime. Note test_current_schema_version_reads_project_yaml passes in dev and would not catch this — it asserts the non-fallback path, in the only environment where that path works.', 'in_progress', 'medium', NULL, 'client', 'D-255', '2026-08-14 21:19:17.188', '2026-08-14 21:21:35.097', NULL, '0e36862b9cbd420d1f0d8114f7673cc9', 2) ON CONFLICT(record_id) DO UPDATE SET type=excluded.type, parent_record_id=excluded.parent_record_id, title=excluded.title, description=excluded.description, status=excluded.status, priority=excluded.priority, assigned_to=excluded.assigned_to, team=excluded.team, decision_ref=excluded.decision_ref, updated_at=excluded.updated_at, deleted_at=excluded.deleted_at, hash=excluded.hash, canonical_version=excluded.canonical_version WHERE excluded.updated_at >= tickets.updated_at;