bug: SQUAD_PERSONAL_DIR env var is documented in SKILL.md but not implemented #1278

Summary

The personal squad SKILL.md template (deployed to every project via squad init) documents a SQUAD_PERSONAL_DIR environment variable that allows users to override the personal squad directory path. This variable is not read anywhere in the SDK — only SQUAD_NO_PERSONAL is checked.

Reproduction

export SQUAD_PERSONAL_DIR=/my/custom/personal-squad
squad cast  # personal squad is NOT loaded from /my/custom/personal-squad

Inspecting the installed SKILL.md (cat .copilot/skills/personal-squad/SKILL.md):

## Environment Variables
- `SQUAD_NO_PERSONAL` — Set to any value to disable personal squad discovery
- `SQUAD_PERSONAL_DIR` — Override the default personal squad directory path

Expected behavior

Either:

1. SQUAD_PERSONAL_DIR is implemented — setting it should cause resolvePersonalSquadDir() to return that path (if it exists), bypassing the platform-specific default, or
2. SQUAD_PERSONAL_DIR is intentionally not supported — in which case it should be removed from both SKILL.md template files so users are not misled.

Actual behavior

SQUAD_PERSONAL_DIR is silently ignored. resolvePersonalSquadDir() always computes the path from resolveGlobalSquadPath(), with no env var override.

Relevant source: packages/squad-sdk/src/resolution.ts, resolvePersonalSquadDir() (line 442).

Affected template files:

• packages/squad-cli/templates/skills/personal-squad/SKILL.md
• packages/squad-sdk/templates/skills/personal-squad/SKILL.md

Environment

• squad-cli: v0.10.0
• squad-sdk: v0.10.0
• OS: any
• Node: v22+