P1 deep-dive: platform, security, subagents, skills, profile + installer fix

PLATFORM (gyandoot-platform):
- Telegram adapter: Long-polling, sendMessage, sendDocument, chat actions
- Discord adapter: REST polling, Bearer auth, channel discovery
- Webhook adapter: Hyper v1 HTTP server, HMAC-SHA256 verification
- CLI UX: Robot head banner, spinner, confirm prompts, colored output

SECURITY (gyandoot-security):
- CredentialVault: AES-256-GCM encrypted per-key files in ~/.gyandoot/vault/
- Sanitizer: PII redaction (email, phone, API keys, IPs), control char stripping
- ThreatDetector: Prompt injection, jailbreak, exfiltration detection with severity

SUBAGENTS (gyandoot-subagents):
- SubAgentWorker: Isolated agent loop with tool filtering and workdir
- SubAgentManager: Bounded concurrency via tokio::Semaphore
- Full lifecycle tracking and result collection

SKILLS (gyandoot-skills):
- SkillsManager: scan, load, inject_skills with YAML frontmatter parsing
- Preprocessor:  template resolution
- SkillBundle: JSON bundle serialization

PROFILE (gyandoot-profile):
- Profile struct with builder and validation
- ConfigResolver: env > symlink > profile > default chain
- ProfileManager: create, list, switch, delete, CRUD with real filesystem ops

INSTALLER FIX: Fixed camofox-browser directory escaping bug that caused
'could not find Cargo.toml' on macOS. Always CD back to project root.

crates/gyandoot-security/Cargo.toml

@@ -18,4 +18,7 @@ hmac.workspace = true
 aes-gcm.workspace = true
 base64.workspace = true
 rand.workspace = true
-chrono.workspace = true
+dirs.workspace = true
+
+[dev-dependencies]
+tempfile = "3"