Normalize task manager and team identities to canonical dave and rj slugs

Problem

Rename team member files from davefowler.md/rj-andrews.md to dave.md/rj.md, update _team_identity_slug() to return nickname instead of file stem, and migrate all frontmatter references to canonical slugs.

Context

• Team member files are named davefowler.md and rj-andrews.md but canonical slugs are dave and rj (the nickname field).
• _team_identity_slug() in tasks/tools/task_cli.py returns path.stem (e.g. davefowler), so completed_by and other fields get non-canonical values.
• get_workstream_owner() defaults to davefowler instead of dave.
• Role files use owner: davefowler and filled_by: rj-andrews instead of canonical slugs.
• ~84 completed tasks have completed_by: davefowler, 3 have completed_by: rj-andrews.
• Runtime state in .tasks/task_manager/ has split keys (dave vs dave-fowler).
• RJ_IDENTITIES / DAVE_IDENTITIES in scripts/task_manager_lib.py enumerate aliases but the root cause is that non-canonical forms are produced in the first place.

Key files: - tasks/team/davefowler.md → rename to tasks/team/dave.md - tasks/team/rj-andrews.md → rename to tasks/team/rj.md - tasks/tools/task_cli.py — _team_identity_slug(), get_workstream_owner() - tasks/team/roles/*.md — owner and filled_by fields - tasks/workstreams/*/tasks/*.md — completed_by frontmatter - scripts/task_manager_lib.py — identity sets (keep as backward-compat aliases) - tests/scripts/test_task_manager_scripts.py — test fixtures

Possible Solutions

A. Rename files + return nickname from _team_identity_slug() (Recommended)

Rename team files to dave.md / rj.md so the file stem matches the canonical slug. Update _team_identity_slug() to prefer nickname over path.stem. Migrate all existing frontmatter references.

• Pro: Single source of truth — the file name IS the canonical slug.
• Pro: _team_identity_slug() returns the right value without special-casing.
• Pro: Eliminates the root cause of non-canonical forms.
• Con: Bulk frontmatter update across ~90 task files.

B. Keep file names, only change _team_identity_slug() to return nickname

• Pro: Smaller diff — no file renames.
• Con: File stem and canonical slug diverge, causing confusion.
• Con: Doesn't clean up existing non-canonical references.

Plan

1. Write a failing test that _team_identity_slug("Dave Fowler") returns dave (not davefowler).
2. Rename tasks/team/davefowler.md → tasks/team/dave.md and tasks/team/rj-andrews.md → tasks/team/rj.md.
3. Update _team_identity_slug() to return nickname when matched, falling back to path.stem.
4. Update get_workstream_owner() default from davefowler to dave.
5. Update role files: owner: davefowler → owner: dave, filled_by: rj-andrews → filled_by: rj.
6. Bulk-update task frontmatter: completed_by: davefowler → completed_by: dave, completed_by: rj-andrews → completed_by: rj.
7. Update test fixtures that use davefowler / rj-andrews as person identities.
8. Run just task validate and just ci.

Implementation Progress

• Wrote failing test test_team_identity_slug_returns_canonical_nickname proving _team_identity_slug returns file stem instead of nickname.
• Fixed _team_identity_slug() to return nickname from team file frontmatter when present, falling back to path.stem.
• Renamed tasks/team/davefowler.md → dave.md and tasks/team/rj-andrews.md → rj.md.
• Updated get_workstream_owner() default from davefowler to dave.
• Updated all 7 role files: owner: davefowler → dave, filled_by: rj-andrews → rj.
• Bulk-updated ~80 task files: completed_by: davefowler → dave, completed_by: rj-andrews → rj.
• Updated test fixtures in test_task_cli.py, test_tasks_activity.py, test_task_manager_scripts.py.
• All 100 focused tests pass.
• Review feedback: fixed 3 missed index files (tasks/team/index.md, tasks/guidebook/index.md, tasks/concepts/index.md) — updated owner: davefowler → dave and fixed broken member links in team/index.md.
• Updated stale context references in make-task-manager-route-tasks-by-role-owner-mapping.md.

QA Exploration

N/A — pure backend/infra change with no UI surface.

• [x] QA exploration completed (or N/A for non-UI tasks)

Review Feedback

• [ ] Review cleared