fix: add user-global tier to agent prompt resolution

[shivchander]

Closes #1264

Changes

• Widen AgentRole from Literal[...] to str so plugin-defined roles are accepted without hardcoding every possible value
• Add user-global prompt tier (~/.factory/agents/prompts/<role>.md) between project-local and factory default in resolve_prompt() — plugins that install agent prompts to this directory are now discoverable
• Update error message to mention the user-global path when no prompt is found
• Update test that asserted AgentRole was a Literal to verify it's now str

[github-actions]

Sentrux Quality Report

Absolute

Scanning ....
[scan] git ls-files: 609 total, 597 kept, 12 dropped (ext:12, meta:0, big:0)
[build_project_map] 597 files, 102 unique dirs, 94 cache misses, 5.9ms
[resolve] 1088 resolved, 1535 unresolved (of 2623 total specs)
[resolve_imports] project_map 6.0ms, suffix_idx 1.1ms, suffix_resolve 17.5ms, total 24.6ms
[build_graphs] 597 files | maps 2.4ms, imports 24.8ms, calls+inherit 6.5ms, total 33.8ms | 1087 import, 8621 call, 11 inherit edges
sentrux check — 3 rules checked

Quality: 4789

✗ [Error] max_cc: 3 function(s) exceed max cyclomatic complexity of 30
    factory/cli/_ceo_helpers.py:_validate_ceo_flags (cc=43)
    factory/cli/_ceo_helpers.py:_execute_ceo (cc=43)
    factory/cli/run.py:cmd_run (cc=32)

✗ 1 violation(s) found

Diff (vs base branch)

Scanning ....
[scan] git ls-files: 609 total, 597 kept, 12 dropped (ext:12, meta:0, big:0)
[build_project_map] 597 files, 102 unique dirs, 94 cache misses, 5.8ms
[resolve] 1088 resolved, 1535 unresolved (of 2623 total specs)
[resolve_imports] project_map 5.9ms, suffix_idx 1.1ms, suffix_resolve 17.5ms, total 24.6ms
[build_graphs] 597 files | maps 2.3ms, imports 24.7ms, calls+inherit 5.8ms, total 32.8ms | 1087 import, 8621 call, 11 inherit edges
sentrux gate — structural regression check

Quality:      4790 -> 4789
Coupling:     0.79 → 0.79
Cycles:       3 → 3
God files:    3 → 3

Distance from Main Sequence: 0.38

✗ DEGRADED
  ✗ Complex functions increased: 53 → 54

[codecov]

Codecov Report

❌ Patch coverage is 20.00000% with 12 lines in your changes missing coverage. Please review.
✅ Project coverage is 86.30%. Comparing base (4129ba2) to head (90b80b5).

Files with missing lines	Patch %	Lines
factory/agents/runner.py	20.00%	11 Missing and 1 partial ⚠️

❌ Your patch check has failed because the patch coverage (20.00%) is below the target coverage (79.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1268      +/-   ##
==========================================
- Coverage   86.34%   86.30%   -0.05%     
==========================================
  Files         211      211              
  Lines       23054    23067      +13     
  Branches     3627     3631       +4     
==========================================
+ Hits        19906    19907       +1     
- Misses       2308     2319      +11     
- Partials      840      841       +1     

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.