feat: success path tail/head strategies for learned patterns

[randomm]

Task Description

Currently, the success path in pattern TOML only supports pattern (regex) + summary (template). The failure path supports tail, head, grep, and between strategies with configurable line counts.

For some commands, agents want to see the last N lines of successful output (e.g., test summary, coverage summary) rather than a single regex extraction. There is no mechanism for this on the success path.

Proposed Design

Allow success section to use the same strategies as failure:

[success]
strategy = "tail"
lines = 10

This would show the last 10 lines of output on success, which is useful for:

• Test runners (summary at the bottom)
• Coverage tools (summary at the bottom)
• Build tools (artifact paths at the bottom)

Quality Gates (Non-Negotiable)

• TDD: Write tests before implementation
• Coverage: 80%+ test coverage for new code
• Linting: All code passes project linting rules
• Local Verification: All tests pass locally

Acceptance Criteria

• Success section supports strategy field (tail, head, grep)
• Existing regex+summary patterns continue to work unchanged
• Tests verify both old and new success formats