feat(detect): MITRE ATLAS 5.6 agentic coverage — 40 new community rules, built-in catalog, rules list, enforced mappings (v0.14.0)

[efij]

Why

Audit of the shipped detections against MITRE ATLAS 5.6.0 and ATT&CK found: zero ATLAS mappings in the rule packs, only 2 CRITICAL rules, and no rules at all for the ATLAS agentic technique family (AML.T0080 context poisoning, T0081 agent config modification, T0083 credentials from agent config, T0084 agent config discovery, T0086 exfiltration via tool invocation, T0090 credential dumping, T0101 destruction via tool invocation, T0103 deploy agent, T0110 tool poisoning). Several built-ins still pointed at pre-5.x IDs (plugin compromise instead of tool poisoning).

What

• community-pack v3: +40 rules → 77 total, 58 HIGH/CRITICAL, every one mapped; mitre_atlas added to 22 existing rules. Starter pack v2.
• Built-in mappings completed/updated across detect, mcpaudit, provenance (see CHANGELOG 0.14.0).
• internal/catalog: machine-readable index of all 51 built-in rules. Test fails the build when a RuleID in source has no catalog entry (or vice versa), when a HIGH/CRITICAL rule has no mapping, or when an ATLAS ID is not a real technique.
• Embedded ATLAS 5.6.0 technique table (scripts/gen-atlas-ids.sh), rulepack.ValidATLAS.
• Hit/miss sample table for every new rule (internal/rulepack/mitre_test.go, ~120 samples).
• agentdfir rules list [--packs dir] [--json].
• docs/detection-coverage.md, generated from the binary by scripts/coverage-matrix.sh.

Result

Rules (built-in + packs)	132 (51 + 81)
HIGH/CRITICAL	88, 86 mapped (2 exempt by name: ORPHAN_AGENT, CROSS_SESSION_MESSAGE — topology/evidence rules)
Distinct ATLAS techniques	27 (was 3)
Distinct ATT&CK techniques	65

go test ./... green locally; shellcheck clean; packs validate with the real loader.