docs(governance): D-104 — explicit supporter-binary path overrides (T-495)

clide resolves external supporter binaries (claude, d2, future tools)
via an explicit user-scope tools: map (name → absolute path), consulted
first. First run auto-detects each tool once and writes the discovered
absolute paths into the map — a one-time populate, pinned thereafter, not
a per-launch heuristic. Escapes the login-shell-probe brittleness (T-439
misses brew when shellenv lives only in ~/.bashrc) while staying zero-
config for standard installs. User-scope only (D-93); generalizes D-58's
CLIDE_PQL_BIN override. Filed T-495; gates the d2 template (T-494).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

governance/README.md

@@ -145,6 +145,7 @@ You might also want, project-permitting:
 - [D-101: ClideSettings — one live-preferences access facade](decisions/architecture.md#d-101-clidesettings--one-live-preferences-access-facade) — _architecture_
 - [D-102: i18n routing — ext-id namespaces, `core` catalog, ClideSettings.i18n facade, contribution keys](decisions/accessibility.md#d-102-i18n-routing--ext-id-namespaces-core-catalog-clidesettingsi18n-facade-contribution-keys) — _accessibility_
 - [D-103: Drawing-card primitive layer is SVG; the SVG renderer is the engine](decisions/architecture.md#d-103-drawing-card-primitive-layer-is-svg-the-svg-renderer-is-the-engine) — _architecture_
+- [D-104: Explicit supporter-binary path overrides in user-scope settings](decisions/tooling.md#d-104-explicit-supporter-binary-path-overrides-in-user-scope-settings) — _tooling_
 
 ## Open questions