feat: add HCL/Terraform language support

[vnz]

Summary

Adds HCL/Terraform support to AiDex. Indexes .tf, .tfvars, and .hcl files with semantic mapping approved in #7:

• Blocks (resource, module, variable, output, data, locals, provider, ...) → types with dotted names (e.g. resource.aws_instance.web)
• Function calls → methods
• Attributes → properties
• Identifiers + block labels → items (searchable via aidex_query)

⚠️ Stacked on #8 — this PR targets master but depends on #8 (tree-sitter 0.21 → 0.25 bump). The HCL grammar requires tree-sitter ^0.25.0. Once #8 merges, this PR's diff will collapse to only the HCL changes.

Key design decisions

Block name composition

HCL blocks have a type keyword plus 0-2 string labels. Composed into dotted names:

• resource "aws_instance" "web" → resource.aws_instance.web
• variable "region" → variable.region
• locals → locals

Label indexing bypasses keyword filter

Block labels are user-chosen identifiers. Terraform-common names like default, root, type, data happen to collide with HCL_KEYWORDS but are meaningful here — so the filter is skipped for the label portion of block names (everything after the block type keyword).

Viewer syntax highlighting

Highlight.js has no HCL language module in the base bundle. .tf files fall back to plaintext rather than emitting an unknown-language class that throws.

Terraform project discovery

Added *.tf (glob) and .terraform.lock.hcl (exact) to PROJECT_MARKERS so global_init --index-unindexed discovers Terraform-only repos.

File watcher deduplication

The viewer's live re-indexing watcher previously used a hardcoded regex for supported extensions (also missing .cxx, .mjs, .cjs, .rake, .pyw from before HCL). Replaced with the parser's isSupported() — now automatically tracks whatever the parser supports.

Validation

Comprehensive test against a real Terraform file with 8 block types (resource, variable, module, output, data, locals, provider, nested filter):

• ✅ All 8 blocks indexed as types with correct dotted names
• ✅ Block labels (vpc, ubuntu, aws, aws_ami) searchable as items
• ✅ Keyword-like labels (default, root, type, data) indexed
• ✅ Block type keywords (resource, variable) correctly filtered
• ✅ Function calls (lookup, templatefile) captured as methods
• ✅ Attribute lines correctly classified as property even when containing function calls
• ✅ Summary reports HCL/Terraform in languages list
• ✅ .terraform/ directory excluded from indexing and watching

Notable review feedback addressed

Codex review surfaced 8 cross-cutting integration points across 5 rounds:

1. 5 hard-coded extension maps (init, global-init, summary, global-database, viewer)
2. Block labels missing from searchable items table
3. Over-aggressive keyword filtering on user-chosen labels
4. PROJECT_MARKERS for Terraform discovery
5. Viewer highlight.js unknown language error
6. File watcher regex drift
7. Attribute/function_call line type conflict
8. .terraform/ working directory not excluded

All resolved. Final Codex review: clean.

Test plan

• Build passes on Node 22 after chore: bump tree-sitter 0.21→0.25 and all grammar packages #8 merges
• Index a real Terraform project (e.g., terraform-aws-modules/terraform-aws-vpc)
• Verify aidex_query term="aws_instance" finds resource declarations
• Verify aidex_signature shows block types with labels
• Confirm summary reports HCL/Terraform
• Confirm .terraform/ is excluded
• Open the viewer and browse .tf files

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