feat(view): add source links to rendered diagrams

[devin-ai-integration]

What and why

Rendered diagrams can now link every node and edge back to its declaration. A link template with {file}, {line}, {col}, {qname} and {id} is set on view.Options.Links and written by every graph form:

• DOT: URL= and tooltip= (qualified name, else file:line:col) on nodes and edges. A composite node puts them on its cluster, so the SVG links the visible box.
• PlantUML: [[url]] on node declarations (after stereotypes, before palette colours) and on edges. Ports, pseudostates (<<start>>, <<fork>>, <<join>>, <<end>>, <<choice>>, <<history>>, <<history*>>) and initial arrows stay unlinked, because the pinned jar drops those links from the SVG. Inside a linked composite state, the jar gives an unlinked pseudostate the composite's link.
• Mermaid: click <id> href "<url>" on flowchart nodes and simple states, link <id>: Source @ <url> on sequence participants. Edges, subgraphs and composite states have no Mermaid link syntax. Mermaid drops the URL fragment (#L26) from sequence participant links in SVG.

Surfaces: CLI -render-link '<template>' (with -render, -render-all and document rendering), REPL %render … link=<template>, LSP opensysml/render linkTemplate, document backends (Markdown/HTML/PDF diagrams), and the VS Code export, which sends <uriScheme>://file/{file}:{line}:{col}.

Decisions:

• {file} is the source path as loaded (slash-normalised), not rewritten against a root; absolute input paths are recommended for vscode:///file:// templates.
• {id} is the element's effective id from identity.Of (declared elementId or the derived one, per element-identity-annotations.md).
• Zero/synthetic origins, bundled library declarations and non-file documents are not linked.
• Substituted values percent-encode everything but unreserved characters, / and :; template literals keep URL delimiters (#, ?, &, %) and escape grammar-unsafe bytes (space, ", ], braces, non-ASCII).
• No template means no change: every existing golden is untouched and a test asserts byte identity.
• The HTML document backend has no per-element sections today, so diagram nodes use the template rather than a same-document anchor.
• The LSP freezes source sites under the workspace lock, and only when a template is given.
• Mermaid's securityLevel is left at its default (strict). Measured with the pinned mermaid-cli 11.16.0: strict mode strips non-HTTP(S) schemes (vscode://, file:///), and loose keeps them. This is documented, not changed.

Specification basis

Diagram rendering is tool-defined (SysML v2 §8.2.2.2). The "hyperlinks are not written" limitation is removed from docs/project/view-rendering-forms.md, and a source-links row is added to the rendering table in docs/project/spec-compliance.md.

How it was verified

• go build ./..., go vet ./..., make lint, go test ./..., plus go test -race on internal/frontend/lsp and internal/workspace/model; make man-check, make docs-counts.
• internal/ir/view/links_test.go: linked goldens for DOT, PlantUML and Mermaid (tree, interconnection, state, action, sequence), escaping (spaces, ], quotes, #, non-ASCII), zero origins, anonymous elements, invalid templates, no-template byte identity. Surface tests for CLI, REPL, LSP, workspace and document rendering.
• SVG survival, all three checked: Graphviz dot -Tsvg writes <a xlink:href>/xlink:title; the pinned PlantUML jar (1.2026.8, -tsvg) writes node and edge <a>, and every link the writer emits has its own href in the SVG; mermaid-cli 11.16.0 writes <a> for flowchart, state and sequence links (HTTP(S) only under strict mode). The tests run all three when the tools are present.
• End-to-end runs: the CLI across 17 view/form combinations and -render-all, the REPL, and the HTML backend, where clicking a linked state opens its source at #L59. In VS Code, a diagram-panel export gave an SVG whose link opened the file at Ln 43, Col 9. A path with spaces, ] and é opened from the Graphviz SVG. With no template, all 17 outputs were byte-identical to develop.

Graphviz SVG in Chrome, hovering tank : Tank (tooltip shows the qualified name, the status bar shows the source URL), and VS Code opened from the exported SVG's link:

Checklist

• make test and make lint pass locally
• Tests added or updated for the change
• Documentation extended where it already covers the surface (see CONTRIBUTING.md)
• Changelog entry added as changes/unreleased/<slug>.<section>.md, not as an edit to CHANGELOG.md
• baselines regenerated and make docs-counts run if a gate count moved (compliance rows need nothing: the census is counted at docs build)
• No internal work-item labels (waves, slices, F4, K5) in the body, docs, or changelog

Link to Devin session: https://nasa-jpl-demo.devinenterprise.com/sessions/c9d4fd36122441dabea9dd6883c66b06
Open in Devin Desktop: https://nasa-jpl-demo.devinenterprise.com/desktop/session/c9d4fd36122441dabea9dd6883c66b06?variant=devin
Requested by: @HuiJun

[devin-ai-integration]

I'll fix CI failures and address comments from users with write access. I'll skip comments containing "(aside)".

• Disable automatic comment, CI, and merge conflict monitoring