docs: expand lifecycle hooks guide with competitive positioning (refs #3316)

[OneStepAt4time]

Summary

Expands docs/hooks-guide.md into a full competitive positioning document showing why Aegis's MCP-integrated hook architecture is architecturally superior to shell/HTTP-only approaches.

Closes #3316

Changes

• Complete event reference — all 29 CC lifecycle events organized by category (session, tool, agent, context, file, worktree, MCP)
• Side-by-side comparisons — concrete config/code examples for Aegis vs cc-connect (TOML), native CC (shell), OpenACP (HTTP)
• Feature matrix — 16 capabilities across 4 tools
• Architecture explanation — why "service mesh" beats "point-to-point" for production orchestration
• MCP bidirectional integration — observe AND act, not just react
• Security model — expanded with session validation, event allowlist, circuit breaker details
• Circuit breaker docs — configurable thresholds, automatic reset behavior

Scope

Documentation only. No code changes.

Verification

• All 29 events match KNOWN_HOOK_EVENTS in src/hooks.ts
• Permission policy example matches evaluatePermissionProfile API
• Circuit breaker defaults match source code constants
• Feature matrix consistent with competitive-threat-matrix.md
• No broken internal links

Review

Argus for merge. This is positioning ammo — accuracy on competitive claims matters.

[aegis-gh-agent]

✅ Approved — clean docs PR, all 9 gates pass.

Review notes:

• Comprehensive event reference (29 events across 6 categories) — well-organized
• Competitive comparison uses concrete config examples (cc-connect TOML, native CC shell, OpenACP HTTP) — fair and verifiable
• Feature matrix (16 capabilities × 4 tools) — useful for decision-makers
• Architecture explanation ("service mesh vs point-to-point") is clear and accurate
• MCP bidirectional integration section adds genuine insight
• Circuit breaker and answer timeout docs now properly detailed
• All internal links resolve (competitive-threat-matrix.md exists)
• No secrets, no internal paths, no plans/specs leakage
• CI green (14/14), MERGEABLE, targets develop

Ready to squash merge.

[aegis-gh-agent]

✅ Reviewed and merged.

Documentation-only change expanding docs/hooks-guide.md. All 9 merge gates pass:

• CI green — 16/16 checks passing
• Targets develop — correct
• No conflicts — MERGEABLE
• Content quality — Complete 29-event taxonomy, side-by-side config examples (cc-connect, native CC, Aegis), 16-capability feature matrix, circuit breaker docs, MCP bidirectional architecture explanation
• Security clean — docs only, no code changes
• Issue linked — Closes #3316
• No internal plans in wrong directory — clean

Squash merged as 3edc078.