emrg: remove GUI 'working directory' (project_dir) concept

[argszero]

Remove the GUI's global 'working directory' (project_dir) concept, per host design-finalized rant 2026-08-20T16:03:31. A session's real cwd is its project path (projectPath); the global project_dir was only a fallback for no-project contexts — the host confirmed it is useless.

Changes

• config.toml [gui] project_dir: no longer read, written, or validated
• main.js: projectDir variable → fixed DEFAULT_CWD = os.homedir(); fallback cwd for first-launch/session-less IPC = home; skills dir fallback = home; getSettings/saveSettings no longer carry projectDir
• Settings panel: workdir tab removed (6 → 5 tabs: model/github/appearance/language/about); settings-body-workdir block deleted
• Welcome page: step 2 'choose a working directory' removed (only API key + default model + save)
• daemon_client.js: TOKEN_FILE/EMRGD_LOG fixed to canonical ~/.emrg/emrgd.token / ~/.emrg/emrgd.log; projectDir constructor param and G129 fallback logic removed (emrgd.token is the sole canonical location since emrg: daemon auth credentials emrgd.port → emrgd.token — single-line token, constant port (rant 2026-08-20T14:32:52) #884)
• conn-manager.js: projectDir passthrough removed
• renderer app.js: state.projectDir gone; project_dir_valid startup check gone; sessionProjectName() no-project fallback → 'home'; projectPathFor() no-project fallback → ''
• dialogs.js / index.html / i18n.js: workdir inputs, tabs, step2, and i18n keys removed
• Tests: all projectDir/workdir assertions cleaned; the two G129 fallback tests rewritten for the single-canonical-location semantics (honest failure instead of fake reuse)

Verification

• GUI: 253 tests — 246 pass, 7 integration fail locally by design (CI skips integration; real daemon holds port 56031)
• pytest: 980 passed + 1 skipped; import + CLI OK
• grep: no projectDir / project_dir / workdir references left in GUI code (only historical comments)

[argszero]

✅ LGTM — cycle 1 (12 files: GUI project_dir concept removed — DEFAULT_CWD=home, daemon_client fixed to canonical ~/.emrg/emrgd.token, settings 5 tabs, welcome no step2, app.js home/'' fallbacks; GUI 246 unit + pytest 980 green, test + test-windows CI PASS)

[argszero]

✅ LGTM — cycle 2 (independent re-review: head unchanged, 12 files −277/+161, GUI project_dir concept cleanly removed with canonical token path; GUI 246 unit + pytest 980 green, test + test-windows CI PASS)

[argszero]

✅ LGTM — cycle 3 (independent re-review: 12 files −277/+161, GUI project_dir concept fully removed — DEFAULT_CWD=home, daemon_client reads canonical ~/.emrg/emrgd.token only (G129 fallback gone), settings 5 tabs, welcome no step2, home/'' fallbacks in app.js; GUI 246 unit + pytest 980 green, test + test-windows CI PASS)