fix(tui): Ecosystem screen — path resolution + row-select + Schedule infusion (PR-A)

[flg77]

Summary

Repairs every dead operator action in the Ecosystem screen the user surfaced via screenshots + notes on 30-Apr-2026. Four bugs collapse to one root cause + one antipattern.

Bugs fixed

#	Symptom	Root cause
1	SKILLS / MCP SERVERS tables show "no skills loaded" / "no MCP servers loaded" guidance rows even though `skills/echo` and `mcps/echo_server` exist.	`_roles_root() / _skills_root() / _mcps_root()` returned bare relative strings. When the TUI launches from outside the repo root (pip-install entry point, container with `WORKDIR=/app`), those resolve against `os.getcwd()` — partial-resolution mismatch is exactly what the screenshot shows.
2	ROLE DETAIL panel never updates on row highlight or click.	Bare `except Exception: pass` blocks swallow every failure silently.
3	"Schedule infusion → Nucleus" button stays disabled / does nothing.	The row-select handler set `_selected_role` AFTER `_show_role_detail()`, so any failure in the detail render silently dropped the selection state and left the button disabled.
4	No log lines an operator could investigate from.	Same bare `except` antipattern.

Surface added

`acc/tui/path_resolution.py` (new)

```python
def resolve_manifest_root(env_var: str, default_dir_name: str) -> Path:
```
Resolution order:

1. `ACC_*_ROOT` env var IF the path exists. If the env var points to a missing dir, warns and falls through — no silent use of bad config.
2. Repo-anchored: `/<default_dir_name>` computed from this module's location. Works in editable installs AND container layouts.
3. `Path.cwd() / default_dir_name` as last-resort fallback so the test harness keeps working.

`acc/tui/screens/ecosystem.py` (changed)

• Three `_*_root` helpers delegate to the new resolver.
• New handler `on_data_table_row_highlighted` — cursor scrolling over a role row now updates ROLE DETAIL live (without pressing Enter).
• `on_data_table_row_selected` rewritten: `_selected_role` is set BEFORE the detail render, behind a shared `_arm_infusion_button()` helper so highlight + select paths share logic.
• `_extract_role_name` static helper handles RowKey API variations across Textual versions.
• Every bare `except Exception: pass` → `logger.exception(...)`.
• `on_button_pressed` now calls `self.notify(...)` with `severity="warning"` when no row is selected — the dead-click becomes visible toast feedback.

Tests (10, all green)

`tests/test_ecosystem_screen_pilot.py`:

Category	Tests
Path resolver (unit)	env-var wins / repo anchor fallback / missing env path warned-and-skipped
Tables populate (Pilot)	skills_table_populated / mcps_table_populated
Row select (synthetic event)	row_selected_handler_directly / row_selection_arms_infusion_button
Row highlight (synthetic event)	row_highlighted_handler_directly
Button (Pilot)	button_press_with_selection / button_press_without_selection_notifies

Why synthetic events instead of `pilot.press("enter")`: Textual's DataTable RowSelected dispatch depends on the widget being the precise focus target at the moment of dispatch — Pilot's harness can't reliably reproduce that in test mode (verified: both `pilot.press("enter")` and `action_select_cursor()` failed deterministically). Constructing `DataTable.RowSelected` / `RowHighlighted` directly and dispatching to the screen's handler exercises the exact same code path Textual would invoke on a real keypress, with no flakiness.

Test plan

• `pytest tests/test_ecosystem_screen_pilot.py -v --no-cov` → 10 passed
• `pytest tests/test_config.py tests/test_role_store.py tests/test_guardrails.py tests/test_compliance.py --deselect tests/test_role_store.py::TestEd25519Validation --no-cov -q` → 139 passed
• Manual: `acc-tui` → 6 Ecosystem. Up/Down on role table → ROLE DETAIL updates LIVE. Enter on coding_agent → ROLE DETAIL pinned + Schedule-infusion button enabled. Click → switches to Nucleus with form pre-filled. SKILLS table shows: `echo 0.1.0 LOW —`. MCP SERVERS shows: `echo_server http LOW echo`.

Out of scope

• PR-A2 — in-TUI manifest upload (FilePicker modal). Splits out per the approved plan.
• PR-B — direct prompt pane + open `PromptChannel` Protocol.

Notes file: `C:\Users\micro\Documents\Notes\Notes\Development\AgenticCellCorpus\ACC TUI\TUI Fixes.md`